Systems and methods for networked, in-context, high-resolution image viewing

ABSTRACT

Systems and methods are provided for viewing portions of an image in high resolution and in context with a full image, which is displayed at a base resolution that is lower resolution than the resolution of the high-resolution image. A user can select an area of interest from the base-resolution image for viewing at a higher resolution on the client device. The server, or in some implementations the client device, can generate a high-resolution image representing the area of interest and the client device can display a portion of the high-resolution image in a virtual lens overlaid on the base-resolution image.

RELATED APPLICATIONS

This application claims the benefit of priority as a continuation under35 U.S.C. §120 of U.S. patent application Ser. No. 12/834,806, entitled“Systems and Methods for Networked, In-Context, High Resolution ImageViewing” and filed Jul. 12, 2010, and is related to U.S. patentapplication Ser. No. 12/834,809, entitled “Systems and Methods forCollaborative, Networked, In-Context, High Resolution Image Viewing” andfiled on Jul. 12, 2010, and U.S. patent application Ser. No. 12/834,810,entitled “Systems and Methods for Networked, In-Context, Composed, HighResolution Image Viewing” and filed on Jul. 12, 2010, all three of whichare hereby incorporated herein by reference in their entireties, as ifset forth in full.

TECHNICAL FIELD

The systems and methods described herein generally relates to the fieldof image processing and more specifically to systems and methods forviewing, over a network, portions of an image in high resolution in thecontext of the full image.

BACKGROUND

The ability to view high-resolution images downloaded over a network isimportant for numerous applications. In the medical field, such acapability is of value in the diagnosis and treatment of patients, aswell as for research and physician education. Other applications thatmay benefit from such a capability include engineering, equipmentoperation and maintenance, digital maps, satellite imagery, forensics,etc. High-resolution images can be extremely large, and can exceed theability of a computer system to store and display the images.Furthermore, transmission of entire high-resolution images across anetwork places significant loads on the network and can negativelyimpact an application's response time if the application has to wait forthe image data to be delivered across the network.

SUMMARY

Systems and methods are provided for viewing portions of an image inhigh resolution and in context with a full image, which is displayed ata base resolution that is lower resolution than the resolution of thehigh-resolution image. The full image can be downloaded to a clientdevice from a server, which may be remote from or local to the client,across a network connection. The server can generate the full image at abase resolution from a high-resolution image stored on, generated on, orinput to the server and the server can transmit the full image to theclient device. The base resolution can be selected based on thecapabilities of the client device or network. The client device candisplay the base-resolution image and can be configured to allow a userto select an area of interest that the user would like to view at ahigher resolution. In response, the client device can request ahigh-resolution image corresponding to the area of interest identifiedby the user from the server. The server can then generate ahigh-resolution image for the client device. The high-resolution imagecan be generated from an image of greater than or equal resolutionstored on, generated on, or input to the server. The server transmitsthe high-resolution image to the client device, and the client devicecan display a portion of the high-resolution image in a virtual lensoverlaid on the base-resolution image. The resolution of thehigh-resolution image can be less than or equal to the resolution of themaximum-resolution image stored on, generated on, or input to theserver. In some embodiments, only a portion of the high-resolution imagethat corresponds to the area of interest, or a region of thehigh-resolution image that includes the area of interest, can be sent tothe client device by the server. In some embodiments, the client cangenerate the base-resolution image and high-resolution image from animage of greater than or equal resolution downloaded from the server.

According to one aspect, a computer-implemented method for displaying aportion of a high-resolution image in the context of a base-resolutionimage is provided where one or more processors are configured to performthe steps of the method. The method includes the steps of receiving arequest to view an image at a client device, sending a request to aserver over a network for a base-resolution image that corresponds tothe requested image, receiving the base-resolution image from the serverover the network, displaying the base-resolution image on a display ofthe client device, receiving a request to display an area of interest ofthe base-resolution image in high resolution, sending a request to theserver over the network for a high-resolution image that corresponds tothe base-resolution image, receiving the high-resolution image from theserver over the network, and displaying a portion of the high-resolutionimage corresponding to the area of interest as an overlay of thebase-resolution image at a location that corresponds to the area ofinterest. In some embodiments, the overlay comprises a virtual lens thatcan include accessories, such as a frame and handle.

According to one aspect, a computer-implemented method for displaying aportion of a high-resolution image in the context of a base-resolutionimage is provided where one or more processors are configured to performthe steps of the method. The method includes the steps of receiving arequest to view an image at a client device; sending a request to aserver over a network for a top-resolution image that corresponds to therequested image; receiving the top-resolution image from the server overthe network; generating a base-resolution image based on thetop-resolution image received from the server; displaying thebase-resolution image on a display of the client device; receiving arequest to display an area of interest of the base-resolution image inhigh resolution; generating a high-resolution image based on thetop-resolution image received from the server; and displaying a portionof the high-resolution image corresponding to the area of interest as anoverlay of the base-resolution image at a location that corresponds tothe area of interest. In some embodiments, the overlay comprises avirtual lens that can include accessories, such as a frame and handle.

According to yet another aspect, a computer-implemented method forproviding high-resolution imagery is provided where one or moreprocessors are configured to perform the steps of the method. The methodincludes the steps of receiving a request from a client device for abase-resolution image; generating a base-resolution image based on animage of greater than or equal resolution associated with the requestedbase-resolution image; transmitting the base-resolution image to theclient device via a network connection; receiving a request for ahigh-resolution image associated with the base-resolution image;generating the high-resolution image based on an image of greater thanor equal resolution generated on, input to, or stored on the server andassociated with the requested high-resolution image; and transmittingthe high-resolution image to the client device.

According to another aspect, a computer-implemented method for providinghigh-resolution imagery is provided where one or more processors areprogrammed to perform the steps of the method. The method includes thesteps of receiving a request from a client device for a top-resolutionimage; generating a top-resolution image based on an image of greaterthan or equal resolution generated on, input to, or stored on the serverand associated with the requested top-resolution image; and transmittingthe top-resolution image to the client device via a network connection.

In another aspect, a computer-implemented method for displaying aportion of a high-resolution image in the context of a base-resolutionimage is provided where one or more processors are programmed to performthe steps of the method. The method includes the steps of receiving arequest to view an image at a client device; sending a request to aserver for the image; receiving the image from the server; anddisplaying the image on a display of the client device.

In yet another aspect, computer-implemented method for providinghigh-resolution imagery is provided where one or more processors areprogrammed to perform the steps of the method. The method includes thesteps of receiving a request from a client device for an image,generating, inputting, or retrieving the image, and transmitting theimage to the client device via a network connection.

In an aspect, a technical system for providing high-resolution imageryis provided. The system includes a non-transitory computer readablemedium for storing computer executable programmed modules, and aprocessor communicatively coupled with the non-transitory computerreadable medium for executing programmed modules stored therein. Thesystem also includes a network interface module stored in thenon-transitory computer readable medium and that is configured toreceive over a network a request for an image at a selected resolutionfrom a client device, and transmit the image to the client device overthe network if the client device or a user of the client device hasaccess rights to the image. The system also includes a requestprocessing module stored in the non-transitory computer readable mediumand in communication with the network interface module. The requestprocessing module is configured to receive the request for an image atthe selected resolution from the network interface module, process therequest, and send the requested image at the requested resolution to thenetwork interface module for transmission to the client device. Thesystem also includes an access control module stored in thenon-transitory computer readable medium and in communication with therequest processing module, the access control module being configured toreceive an authorization request from the request processing module toverify access rights of the client device or a user of the client deviceto the requested image, verify the access rights per an access controlpolicy, and send an authorization response to the request processingmodule indicating whether the client device or the user has accessrights to the image. The system also includes an image management modulestored in the non-transitory computer readable medium in communicationwith the request processing module. The image management module isconfigured to process an image management request from the requestprocessing module using a data store.

According to another aspect, a technical system for viewinghigh-resolution imagery is provided. The system includes anon-transitory computer readable medium for storing computer executableprogrammed modules, and a processor communicatively coupled with thenon-transitory computer readable medium for executing programmed modulesstored therein. The system further comprises a network interface modulestored in the non-transitory computer readable medium and that isconfigured to transmit a request for an image to a server over anetwork, the image being request by a user of the system, and receivethe requested image from the server over the network. The system alsoincludes a user interface module stored in the non-transitory computerreadable medium and that configured to receive a request from a user toview an image, receive a base-resolution image corresponding to therequested image, display the base-resolution image on a display of thesystem, receive a request from the user to display an area of interestof the base-resolution image in high resolution, receive a composedimage comprised of a portion of a high-resolution image corresponding tothe area of interest as an overlay of the base-resolution image at alocation that corresponds to the area of interest, and display thecomposed image. The system also includes a request processing modulestored in the non-transitory computer readable medium and incommunication with the user interface module and the network interfacemodule. The request processing module is configured to receive a requestfor the base-resolution image from the user interface module in responseto receiving the request from the user to view the image, process therequest for a base-resolution image from the user interface module,provide the base-resolution image to the user interface module fordisplay to the user, receive a request for a composed image comprised ofa portion of a high-resolution image corresponding to the area ofinterest as an overlay of the base-resolution image at a location thatcorresponds to the area of interest from the user interface module inresponse to receiving the request from the user to view the image,process the request for the composed image, and provide the composedimage to the user interface module for display to the user. The systemalso includes an image management module stored in the non-transitorycomputer readable medium and in communication with the requestprocessing module and network interface module, the image managementmodule being configured to process an image management request using adata store.

These and other features, aspects, and embodiments are described belowin the section entitled “Detailed Description.”

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and embodiments are described in conjunction with theattached drawings, in which:

FIG. 1 is a block diagram illustrating an image viewing system accordingto an embodiment;

FIG. 2 is a flow diagram of a successive download method that can beimplemented on a client device of the image viewing system illustratedin FIG. 1 according to an embodiment;

FIG. 3 is a flow diagram of a successive download method that can beimplemented on a server of the image viewing system illustrated in FIG.1 according to an embodiment;

FIG. 4 is a block diagram of an example display area of a client deviceaccording to an embodiment;

FIG. 5 is a flow diagram of a client downscaling method that can beimplemented on a client device of the image viewing system illustratedin FIG. 1 according to an embodiment;

FIG. 6 is a flow diagram of a client downscaling method that can beimplemented on a server of the image viewing system illustrated in FIG.1 according to an embodiment;

FIG. 7 is a flow diagram of a server composition method that can beimplemented on a client device of the image viewing system illustratedin FIG. 1 according to an embodiment;

FIG. 8 is a flow diagram of a server composition method that can beimplemented on a server of the image viewing system illustrated in FIG.1 according to an embodiment;

FIGS. 9A and 9B are flow diagrams of a collaborative method that can beimplemented on client devices of the image viewing system illustrated inFIG. 1 according to an embodiment;

FIG. 10 is a flow diagram of a collaborative method that can beimplemented on a server of the image viewing system illustrated in FIG.1 according to an embodiment; and

FIG. 11 is a block diagram of the logical components of a serverillustrated in FIG. 1 according to an embodiment; and

FIG. 12 is a block diagram of the logical components of the clientdevice illustrated in FIG. 1 according to an embodiment.

DETAILED DESCRIPTION

Systems and methods are provided that facilitate the viewing ofhigh-resolution portions of an image on a client device using a virtuallens. In response to a user request to view an image, the client devicecan request a copy of the image at a base level resolution from a serverover a network. The server can generate, retrieve from storage, or inputthe base-resolution image from a high quality, high-resolution imagethat is stored on, generated on, or input to the server and transmit thebase-resolution image to the client device. The base-resolution image isof a lower resolution than the high-resolution image that is stored on,generated on, or input to the server, and the resolution of thebase-resolution image can be determined at least in part based on thecapabilities of the client device or network. The client device isconfigured to receive the base-resolution image from the server and todisplay the base-resolution image on a display interface. A user of theclient device can then select an area of interest on the base-resolutionimage, and the client device can request a high-resolution image fromthe server that corresponds to the area of interest identified by theuser, the high-resolution image being of a resolution up to theresolution of the image stored on, generated on, or input to the server.For example, in some embodiments, the client device can be configured torender a “virtual lens” that is overlaid on the base-resolution image atthe area of interest, and to display within the virtual lens the portionof the high-resolution image that corresponds to the area of interest.The virtual lens can thus show a more detailed image of the area ofinterest, enabling the user to “zoom in” on details within an area ofinterest. The size of the virtual lens and the resolution of thehigh-resolution image displayed within it can be determined at least inpart based on the capabilities of the client device or network.

In some embodiments, only a portion of the high-resolution image thatcorresponds to the area of interest or a region of the image thatincludes the area of interest can be sent to the client device by theserver. In other embodiments, a full high-resolution image can be sentto the client device by the server and the client device can beconfigured to select a portion of the high-resolution image thatcorresponds to the area of interest and to display that portion of thehigh-resolution image in the virtual lens.

According to an embodiment, an overlay image provided by the virtuallens can be located on a portion of the full, base-resolution image thatcorresponds to the higher-resolution image displayed by the virtual lensin order to provide context as to the location of the high resolutionportion with respect to the image, as well as select the level ofresolution. This configuration enables viewing of high-resolution imageswithin the available display space of an application while providingcontext to the overlaid image. According to an embodiment, thesetechniques can be used to display high resolution content correspondingto at least a portion of an image, even where the resolution of acomputer system is insufficient to show the full image at highresolution or where it is undesirable to use an amount of display spacethat would be necessary to show an entire high-resolution image.

Some embodiments enable a user to select an area of interest within theimage to be displayed in high resolution, and some embodiments providethe user with the ability to move the area of interest to any part of animage. These techniques can help to reduce the amount of high-resolutionimage data that needs to be sent across the network at a given time, andcan also reduce the amount of display area required on the devicedisplaying the image data as well as processing power, memory, or bothof the client device and server. Furthermore, embodiments can be used tooptimize the response times for various usage scenarios.

FIG. 1 is a block diagram of an image viewing system 100 according to anembodiment. The image viewing system includes a client device 110, aserver 120, and network 130. Client device 110 can be a computing devicecomprising one or more processors, volatile and non-volatile memory,displays, keyboards (hard or soft), pointing devices (e.g., mouse, touchpad, joystick, touch screen, track ball), network interfaces, and otherinput/output devices. The client device 110 can be a desktop computer,laptop computer, a computer workstation, computing pad, computingtablet, document reader, smart phone, cell phone, personal digitalassistant, network appliance, thin client system, digital televisionwith embedded or external processor, memory, and network interface, orother type of device capable of receiving image data over a network anddisplaying the image data to a user of the device. According to someembodiments, the functionality of client device 110 can be implementedin one piece of equipment or be distributed across multiple pieces ofequipment.

Server 120 can be a computing device comprising one or more processors,volatile and non-volatile memory, network interfaces, and otherinput/output devices. According to some embodiments, the functionalityof server 120 can be implemented in one piece of equipment or bedistributed across multiple pieces of equipment. According to someembodiments, the image viewing system 100 can include multiple servers120 that are configured to provide image data to one or more clientdevices 110 via one or more networks 130. The server 120 can, in someembodiments, be a web server that is configured to provide content tothe client device 110 over the network 130. According to an embodiment,the server 120 can be in communication with one or more data stores (notshown) that can be used to store image data to be provided to the clientdevice. According to an embodiment, the data stores can be implementedon the server 120 or can be implemented on a separate data server (notshown). The server can also be in communication with one or more imageinput devices (e.g., a camera, a scanner, a sensor).

According to an embodiment, the network 130 can represent one or morewired or wireless network connections between server 120 and clientdevice 110. According to an embodiment, network 130 includes theInternet, a local area network, a wide area network, a metropolitan areanetwork, a telephone network, a television network, a wireless networkor link, a satellite network or link, a bus, or other type of network orinterconnection method.

According to an alternative embodiment, the functionality of the server120 and client device 110 can be implemented in a single device or pieceof equipment. For example, the techniques disclosed herein can be usedfor viewing data captured by a digital microscope scanning system.

The image viewing system 100 enables a user to view portions of ahigh-resolution image on the client device 110 without requiring thatthe entire high-resolution image be transmitted by the server 120 to theclient device 110. In an embodiment, the client device 110 can beconfigured to display a “base-resolution” image in a display region 150of the client device 110 and a virtual lens 160 overlaid on thebase-resolution image in display region 150. The base-resolution imagecan be a lower resolution representation of a high-resolution imagestored on, generated on, or input to the server 120. Because thebase-resolution image is a lower resolution than the high-resolutionimage, the base resolution image requires less bandwidth to betransmitted over the network 130 to the client device 110. Thebase-resolution image in display region 150 can provide a user of clientdevice 110 with a context in which the user can identify areas ofinterest to be displayed in high-resolution.

The virtual lens 160 can display a high resolution portion of thebase-resolution image in display region 150 at a higher resolution thanthe base-resolution image. According to an embodiment, the resolution ofthe portion of the high-resolution image displayed in virtual lens 160can be the same as the resolution of the high-resolution image storedon, generated on, or input to the server 120. According to anotherembodiment, the resolution of the portion of the image displayed in thevirtual lens 160 can be of a different resolution than thehigh-resolution image stored on, generated on, or input to the server120. For example, the virtual lens 160 can be configured to display aportion of the high-resolution image at a resolution that is betweenthat of the base-resolution image 160 and the resolution of thehigh-resolution image stored on, generated on, or input to the server120. According to an embodiment, the user can select the resolution atwhich the virtual lens 160 displays the image from a discrete set ofresolutions. The image viewing system 100 can determine the resolutionlevels of the discrete set of resolution based in-part on thecapabilities of the client device or network, and the resolution of thebase-resolution image. In another embodiment, the user can select theresolution at which virtual lens 160 displays the image from acontinuous range of resolutions. The image viewing system 100 candetermine the lower and upper bounds of the continuous range ofresolutions based in-part upon the capabilities of the client device ornetwork, and the resolution of the base-resolution image.

According to an embodiment, the high-resolution images can be uploadedto server 120, generated on server 120, or be generated by equipmentcoupled to the server 120, such as a digital scanning microscope, adigital camera, or a scanner.

According to an embodiment, a user of client device 110 can select anarea of interest of the base-resolution image in display region 150 thatcorresponds to a portion of the high-resolution image that the userwould like to view in the virtual lens 160. According to an embodiment,the client device can be configured such that a user can select aportion of the base-resolution image in display region 150 using apointing device of the client device 110, such as a mouse, trackball,touchpad, touch screen, joystick, arrow keys, buttons, or other inputdevice. According to an embodiment, the client device can be configuredsuch that a user can also select a different area of interest using apointing device of the client device 110 by selecting an area on thebase-resolution image in display region 150. According to an embodiment,the client device 110 is configured to display in display region 150 thefull lower-resolution base image overlaid with a portion of thehigh-resolution image corresponding to the area of interest selected onthe base-resolution image. Because the portion of the high-resolutionimage displayed in the virtual lens is of higher resolution than thebase-resolution image, less of the image can be shown in the virtuallens than the area that it covers in the base-resolution image. Thecapability to cause the virtual lens to move using the pointing deviceenables the user of the client device to eventually see all parts of theimage in the virtual lens at high resolution.

The term “resolution,” as used herein, refers to the total number ofpixels of an image and can also refer to the total number of colors perpixel for an image. For example, resolution can refer to the totalnumber of horizontal pixels by the total number of vertical pixels in animage. In yet other embodiments, an optional third dimension can beincluded, and the resolution can include a depth component. Theresolution may also include a time dimension if the image changes intime. With respect to video content, resolution can refer to the totalnumber of frames per second. The resolution can alternatively refer tothe level/quantity of details of an image. For example, the number ofroadways or other features illustrated on a map.

In certain embodiment, three levels of resolution can be used here todistinguish between different resolutions for an image:

Maximum resolution is a resolution that is less than or equal to theresolution at which an image is captured (e.g., via a digital camera,scanner, or sensor), input, or generated (e.g., with image or videoauthoring tools).

Base resolution is a resolution that is sufficient for basic inspectionof an image, as well as sufficient to provide a visual context forviewing a portion of a high-resolution image. The base resolution is alower resolution than the maximum resolution.

High resolution is a resolution that is higher than the base resolutionand less than or equal to the maximum resolution.

Top resolution is a resolution that is greater than or equal to highresolution and less than or equal to the maximum resolution.

In one example, a high resolution still image can be 3648×2736 pixels(horizontal by vertical) with 24-bits of color per pixel, typical ofdigital cameras with 10 megapixel resolution. However, one skilled inthe art will recognize that this is merely one example and that theresolution of the high-resolution images can vary.

A typical high-resolution image can consume a significant amount ofmemory, and can be too large to fully view at the native resolution inthe available area of a client's display. A typical high-resolutionimage can also take a considerable amount of time (e.g., several secondsor more) to download from the server over the network, or can otherwisestress the capabilities of the client, server, or network. In manyapplications, a base (low-to-medium) resolution image can be sufficientfor basic inspection of the image. A user occasionally needs to seeareas of interest of the image at high resolution (higher resolutionthan the base resolution) to inspect details of the image. In certainembodiments, the user is allowed to view a high-resolution portion of animage shown in the context of the base-resolution image.

Some conventional image viewing systems allow a user to magnify aportion of an image, but these systems typically magnify a portion ofthe computer display using digital magnification methods rather thanobtaining and displaying a higher resolution image that can actuallycontain additional detail. In some conventional systems, a portion of abitmap corresponding to an image being displayed to user is digitallyenlarged to create a magnification effect. This approach does notprovide any additional detail, but rather uses digital enhancement of alower resolution image to create the simulated magnified image. Forexample, the pixels in the original lower resolution image can bereplicated to create the simulated magnified image, and one or moresmoothing algorithms might be applied to the magnified image. However,the resulting simulated magnified image can be grainy and can lackadditional detail that was not in the original image. Some conventionalsystems also magnify the whole image rather than just a user-selectedarea of interest within the image. For example, ADOBE READER® andMICROSOFT OFFICE® magnify a whole image or document page rather than auser-selected area of interest within an image or document page.

In contrast, the image viewing system 100 can display in high resolutionuser-selected areas of interest of an image that has been captured orgenerated at a maximum resolution. The client device 110 can display theuser-selected area of interest with up to all of the detail available atthe maximum resolution and can show the area of interest in context ofthe full image at the base-resolution. According to an embodiment, auser-selected area within the image is displayed in high resolutionoverlaid on the full base-resolution image at the area of interestselected by the user.

Conventional systems also do not use a client-server based approach todigital magnification or in-context high-resolution display. Inconventional systems, images or documents are stored locally on acomputer system and all or a portion of the document can be magnifiedusing the conventional techniques described above. In contrast, theimage viewing system 100 can use a client-server based approach wherethe large high-resolution images are stored on, generated on, or inputto the server 120 and a smaller base-resolution image can be transmittedacross the network 130 to the client device 110 for basic inspection.The high resolution image can be transmitted only as needed and notnecessarily for every base-resolution image, thereby saving networkbandwidth as well as processing and memory resources on both the clientdevice and the server. In some embodiment, as a further optimization, ifthe user is expected to require viewing of only a portion of the imagein high resolution, that portion can be transmitted by the server to theclient device across the network 130, rather than the entirehigh-resolution image. Since a high-resolution image can be in the orderof a megabyte or more in size even when compressed, reducing the numberof times that it is transmitted or merely sending across the network theportions of a high-resolution image corresponding to the areas ofinterest that the client device user selects can provide an efficientsystem for viewing images that can provide a good overall response time.

Returning now to FIG. 1, client device 110 of the image viewing system100 can be configured to allow a user to view images stored on,generated on, or input to the server 120 at various resolutions. Thedisplay region 150 on the client device 110 shows a base-resolutionimage and the virtual lens 160 shows a high-resolution portion of theimage that is overlaid over the base-resolution image. According to anembodiment, the display region 150 can be all or part of a displaywindow of an application running on the client device 110, such as webbrowser, a word processing application, an image viewer or editorapplication, or other type of application in which a user might wish toview high-resolution image content.

According to an embodiment, the client device 110 can be configured todisplay the virtual lens 160 using different shapes. For example, thevirtual lens can be rectangular, circular, ovular, or another shape.According to some embodiments, the virtual lens can include accessories,such as a frame and handle. For example, in one embodiment, the virtuallens can be shaped like a magnifying glass in order to provide theillusion of a moveable magnifying glass that overlays thebase-resolution image and within the magnifying glass shaped virtuallens 160, a portion of the high-resolution image associated with thearea of interest selected by the user is displayed. The high-resolutionimage can be transmitted (transmission 140) from the server 120 to theclient device 110 via network 130.

According to an embodiment, the client device 110 can be configured toallow the user to move, using a pointing device, the virtual lens 160over the base-resolution image in display region 150 in order to changethe portion of the high-resolution image displayed in the virtual lens160. As described above, while the virtual lens 160 appears to operateas a magnifying glass on the base-resolution image in display region150, no actual magnification of the base-resolution image is performed.Instead, the virtual lens 160 displays the portion of thehigh-resolution image received from the server 120.

For example, an online medical continuing education course provider canuse the image viewing system 100 to display training slides that includedigital microscope imagery. These digital images can be extremely largein size and can consume a lot of network bandwidth if an entirehigh-resolution image is transmitted from the server 120 to the clientdevice 110. Instead of providing a full sized high-resolution image, theserver 120 can provide base-resolution image of a digital slide thatillustrates a particular concept. If the user would like to see moredetail, the user can select an area of interest on the base-resolutionimage and the client device 110 can present a high-resolution view ofthe area of interest in the virtual lens 160 overlaid over the area ofinterest of the base-resolution image. The user can see a higher levelof detail in the high-resolution image for that image. This approach canmake more efficient use of network and computing resources of the server120 and the client device 110, because the client device does not needto request the high-resolution image from the server 120 for everybase-resolution image viewed. Further efficiencies can be achieved whenthe user only needs to view a portion of the image in high resolution(e.g., a region surrounding a selected area of interest), since onlythat portion may be transmitted from the server to the client device,rather than the entire high-resolution image. In some embodiments, thelocation of the virtual lens 160 can be configured to appear at aparticular location on the base-resolution image in order to highlight aparticular feature from the digital slide that illustrates a point fromthe teaching materials. In some embodiments, the user can alsodynamically control the positioning and the size of the virtual lens160, and the contents of the virtual lens 160 can be dynamically updatedwith high-resolution content from the server 120 as the user changes thearea of interest. In some embodiments, the user can also change thelevel of “magnification” (i.e., the level of resolution) displayed bythe virtual lens. If the user requests that the virtual lens zoom infurther, a higher resolution image can be displayed in the virtual lens(up to a maximum resolution supported by the server), and if the userrequests that the virtual lens zoom out, a lower resolution image can bedisplayed in the virtual lens.

In another example, an online mapping application can use the imageviewing system 100 to display additional details about an area ofinterest, to display more detailed satellite imagery of an area ofinterest, or both. When the user requests a map, the server 120 canprovide a base-resolution map to the client device, and the virtual lenscan be used to provide a detailed view of a portion of the map in thecontext of the base-resolution image, when the user requires a moredetailed view. Thus, the high-resolution image can be downloaded onlywhen needed. In some embodiments, as a further optimization, when theuser's high-resolution viewing requirement is only for a portion of theimage (e.g., a region surrounding a selected area of interest), onlythat portion may be transmitted from the server the client device overthe network. This technique could be particularly useful on mobiledevices that include navigation applications, because these devicesoften have bandwidth and memory constraints.

According to an embodiment, the image viewing system 100 can beconfigured to use three different modes of operation: a successivedownload method, a client downscaling method, and a server compositionmethod. According to some embodiments, these methods can be used aloneor in combination. In another embodiment, the image viewing system 100can be configured to provide a collaborative method that can be used incombination with either the successive download method, the clientdownscaling method, or the server composition method.

Successive Download Method

FIGS. 2 and 3 are flow diagrams of a successive download method that canbe used in conjunction with an image viewing system 100 according to anembodiment. FIG. 2 illustrates the steps of a method for successivedownload that can be performed at client device 110 according to oneembodiment, and FIG. 3 illustrates the steps of a method for successivedownload that can be performed by server 120.

The method of FIG. 2 begins when a client device 110 receives a requestto view an image at the client device (step 210). According to anembodiment, the request can comprise a user accessing a document orimage from an application. In other embodiments, the request cancomprise a user accessing a particular web page or other content from abrowser application running on the client device 110. In yet anotherembodiment, the request can comprise a user executing an application onthe client device 110 that uses high-resolution image content retrievedfrom the server 120.

In the example of FIG. 2, the client device 110 sends a request to theserver 120 for a base-resolution image (step 220) that corresponds tothe image that was requested. According to an embodiment, a displayengine module can be implemented on the client device 110 that isconfigured to process requests for images from applications on theclient device 110 and to send a request via network 130 to the server120 for a base-resolution image that corresponds to the requested image.

A determination is made whether the image was received from the server120 (step 225). According to an embodiment, if access to the image is tobe restricted, the server 120 can make a determination whether the userof the client device or the client device 110 (or both) is authorized toview the image content requested per the access control policy.According to an embodiment, the request sent by the client device 110can include identification information associated with a user or theclient device 110 that can be used in determining whether the server 120should grant access to the image content stored on, generated on, orinput to the server 120. If the user is not authorized to access therequested image, the server 120 can optionally send a message to theclient device 110 indicating that the user or client device 110 is notauthorized to access the requested image. According to an embodiment,the client device 110 can also be configured to keep track of how muchtime has passed since the request was transmitted to the server 120 andto timeout the request if the base-resolution image is not receivedwithin a predetermined amount of time.

If the image is not received from the server 120, the client device 110can optionally display a message to the user indicating that therequested image could not be accessed (step 260). According to someembodiments, a detailed error message can be generated that describeswhy the image could not be accessed. For example, the message canindicate that the request timed out if a response was not receivedwithin a predetermined amount of time, or that the user was notauthorized to view the requested content.

If the image is received by the client device 110 from the server 120,the client device 110 can display the base-resolution image in displayregion 150 of the client device 110 (step 230). According to anembodiment, the display engine of the client device can be configured toadjust the size of the base-resolution image based on the availablespace on the display area of the client device 110 for displaying thebase-resolution image. FIG. 4 illustrates an example of a display areaon a client device. For example, if the client device 110 includes a1200 pixel wide by 800 pixels high display area 410, and if 60% of thewidth of display area is available for displaying the base-resolutionimage 420, and the full height minus 140 pixels at the top of thedisplay area and minus 120 pixels at the bottom of the display area isavailable, the display engine module of the client device will displaythe base-resolution image as a 720 pixel wide by 540 pixel high image onthe display area on the available display area 420. According to anembodiment, the display area 410 can comprise a desktop displayed on ascreen or other display device of client device 110. In an embodiment,the display area 410 can comprise a window of an application, includingthe application information as well as window controls and otherinformation. For example, in some embodiments, a user can accesscontent, such as high-resolution imagery or a web page or other contentthat includes high-resolution imagery from within a browser. In theembodiment illustrated in FIG. 4, a portion of the display area 415 isbeing used for text content, which reduces the available space fordisplaying the base-resolution image. The available space for displayingthe base-resolution image can also be affected if the base-resolutionimage is to be displayed in an application window. As a result, thedisplay area 420 for the base-resolution image can be less than thetotal amount of display area for the client device's display. As can beseen from these example embodiments, the resolution of thebase-resolution image can be based at least in part by the resolutionand screen size of the client device 110 and can also be based on thesize of the display area 420 available for showing the base-resolutionimage.

The client device 110 can then receive a request from the user to viewan area of interest of the image in high resolution (step 235).According to an embodiment, the user can use an input device, such as apointing device, including a mouse, touch screen, touchpad, joystick,trackball, arrow keys, buttons, or other input device that allows theuser to select an area of interest within the base-resolution image thatthe user would like to view in high resolution.

The client device can then send a request to the server 120 for ahigh-resolution image that corresponds to the base-resolution image(step 240). According to an embodiment, the request can include adesired resolution level for the high-resolution image. The desiredresolution can fall into a range above the resolution of thebase-resolution image and up to the resolution of the maximum-resolutionimage stored on, generated on, or input to the server 120.

According to some embodiments, the client device 110 can send a requestto the server 120 for only the portion of the high-resolution image thatcontains the area of interest identified by the user, rather than thefull high-resolution image. The alternative of requesting only a portionof the high-resolution image may be used, for example, if the user isexpected to only view part of the base image in high resolution, of ifthe network transmission time for the full image would adversely affectresponse time, or if client memory size is inadequate for the fullhigh-resolution image. According to an embodiment, the request caninclude a set of coordinates relative to a reference point on thebase-resolution image that correspond to the area of interest. Forexample, in some embodiments, the client device 110 is configured sothat a user can draw a rectangle on the base-resolution image toindicate the area of interest that the user would like to see in highresolution, and coordinates of the left-top and right-bottom corners ofthe rectangle, or the coordinates of the left-top or center point andthe width and height of the rectangle, can be provided to the server 120in the request for the high-resolution image. According to anembodiment, the display engine module can be configured to translatescreen coordinates to pixel coordinates on the base-resolution image,and the request to the server for the high-resolution image can includethe pixel coordinates of the area of interest specified by the user.According to an alternative embodiment, the client device 110 canprovide a user interface where the user can drag or move a cursor or ashape, such as a rectangle or oval, to the location of an area ofinterest on the base-resolution image in order to receive ahigh-resolution image that corresponds to the area indicated by thecursor or covered by the shape.

A determination is made whether the high-resolution image was receivedfrom the server 120 (step 245). If the image is not received from theserver 120, the client device 110 can optionally display a message tothe user indicating that the requested image could not be accessed.Otherwise, if the requested high-resolution image corresponding to thearea of interest is received by the client device 110, the client device110 can display the portion of the high-resolution image correspondingto the area of interest in the virtual lens 160 (step 255). The virtuallens can be positioned over the area of interest on the base-resolutionimage and can be configured to display the portion of thehigh-resolution image that corresponds to the area of interestidentified by the user. According to an embodiment, the virtual lens 160can default to an initial size and shape. In one embodiment, the size ofthe virtual lens can correspond to the size of the base-resolution imagedisplayed on the client device 110. For example, in one embodiment, thesize of the virtual lens might be one fourth of the size of thebase-resolution image. For example, if the size of the base-resolutionimage is 720 pixels wide by 540 pixels high, the size of the virtuallens would be 360 pixels wide by 270 pixels high.

According to an embodiment, the display engine module of the clientdevice 110 can determine the portion of the high-resolution imagecorresponding to the user-selected area of interest and display thecorresponding portion of the high-resolution image in the virtual lens160, replacing the underlying base-resolution image in the area ofinterest with the corresponding portion of the high-resolution image.According to one embodiment, if the user selected horizontal andvertical coordinates [180,270] relative to the left-top on thebase-resolution image as the center of an area to be shown in higherresolution, the virtual lens can be positioned centered at [180,270] onthe base-resolution image. If the resolution of the high-resolutionimage is 1080 pixels wide by 810 pixels high and the portion of thehigh-resolution image to be displayed (e.g., the size of the virtuallens) is 360 pixels wide by 270 pixels high, the center point of thearea to be displayed in the high-resolution image would be [270,405],the point corresponding to [180,270] in the base-resolution image (aquarter of the way across and halfway down). According to someembodiments, a border can also be rendered around the virtual lens 160to demarcate the virtual lens 160 from the base-resolution image indisplay region 150. It should be noted that a smaller area of thehigh-resolution image can be displayed in the virtual lens than the areain the base-resolution image that the virtual lens covers. In thisexample, in a 360×270 virtual lens, approximately 11% of thehigh-resolution image can be shown in the virtual lens((360×270)/(1080×810)). The virtual lens would cover approximately 25%of the base-resolution image ((360×270)/(720×540), not includingborders). The ability to move the virtual lens over the high-resolutionimage enables all parts of the base-resolution image to be viewed inhigh resolution in the virtual lens.

According to an alternative embodiment, in order to improve responsetime, the high-resolution image can be downloaded from the server 120 inadvance of a user's request to view the portion of the high-resolutionimage in the virtual lens 160. In such an embodiment, the portion of thehigh-resolution image is not displayed in the virtual lens 160 untilsuch display is requested by the user. According to an embodiment, thepre-fetch of the high-resolution image can be initiated by some useraction, which can trigger the client device 110 to send a request theserver 120 for the high-resolution image. For example, in someembodiments, the download of the high-resolution image can be requestedat the time the base-resolution image is requested from the server 120,or shortly after the base-resolution image is received from the server.Alternatively, the client device 110 can be configured to initiate thedownload of the high-resolution image in response to the user depressinga soft or hard key (e.g., an “image viewing system activate” button) orby clicking on a pointing device button. Continuing this pre-loadingtechnique, a subsequent download of the image at the next higherresolution can be requested upon completion of each high-resolutionimage download, up to the maximum resolution.

According to an embodiment, the client device 110 can be configured toallow the user to move the virtual lens 160 over the base-resolutionimage in display region 150. In one embodiment, the client device 110 isconfigured such that the user can move the virtual lens using a pointingdevice, such as mouse, touchpad, touch screen, joystick, trackball,arrow keys, or buttons. In an embodiment, the display engine module ofthe client device 110 is configured to change in real time, as the usermoves the cursor across the base-resolution image, the selected area ofinterest and the position of the virtual lens overlaid on it, whilechanging the portion of the high-resolution image displayed in thevirtual lens to correspond to the changed area of interest indicated bythe cursor position. According to an embodiment, the display enginetakes into account the cursor position within the base-resolution imagerelative to a point of reference, such as the left-top corner of theimage to determine the position of the high-resolution image to displaywithin the virtual lens 160. In an embodiment, the display engine modulecan also take into account whether the user has scrolled the display onthe client device display and adjust for horizontal or verticalscrolling amounts (or both). If a portion of the high-resolution imagehad been requested from the server 120 rather than the fullhigh-resolution image, if the cursor moves to a location such that moreof the high-resolution image is needed to fill the virtual lens 160, theclient device 110 can send a request to the server 120 for an additionalportion of the high-resolution image to display in the virtual lens 160.

According to an embodiment, the display engine module of the clientdevice 110 can be configured to allow a user to request a change in thelevel of resolution of the high-resolution image displayed in thevirtual lens 160. According to an embodiment, the display engine modulecan be configured to provide user interface controls, such as softbuttons, sliders, pointer device controls, or other types of interfacecomponents with which the user can interact to select a desired level ofresolution for the high-resolution image displayed in the virtual lens160. In an embodiment, the user can select a level of resolution for theimage displayed in the virtual lens 160 that is up to the maximumresolution level of the image stored on, generated on, or input to theserver 120. In an embodiment, the user can select a level of resolutionthat is up to the maximum resolution and greater than the resolution ofthe base-resolution image.

In response to a request to change the resolution of the portion of theimage displayed by the virtual lens 160, the display engine module canbe configured to send a request to the server 120 for the fullhigh-resolution image or a portion of the high-resolution imagecorresponding to the base-resolution image and the selected resolutionlevel. When a portion is requested, the portion requested may be thesame size as what will be displayed in the virtual lens 160 or larger.The display engine module can display the portion of the high-resolutionimage corresponding to the area of interest in the virtual lens 160 oncethe server 120 sends the high-resolution image to the client device 110over the network 130. When the user requests an increase in resolutionover what is currently being displayed in the virtual lens 160, aportion of the high-resolution image of the requested resolution thatcorresponds to a smaller portion than currently shown of thebase-resolution image will be displayed in the virtual lens 160. Whenthe user requests a decrease in the resolution relative to what iscurrently being displayed in the virtual lens 160, a portion ofhigh-resolution image that corresponds to a larger portion thancurrently shown of the base-resolution image will be displayed in thevirtual lens 160. According to an embodiment, the server 120 can have aplurality of images of different resolutions for a particularbase-resolution image stored in memory, each image in the plurality ofimages generated from an image of greater than or equal resolutiongenerated on, input to or stored on server 120, or the server 120 canstore the maximum-resolution image in memory and generate otherhigh-resolution images (of lower resolution than the maximum) uponrequest from the client. According to an embodiment, a user can changethe resolution displayed by the virtual lens 160 on the fly.

According to an embodiment, the display engine of the client device 110can also be configured to allow a user to change the size of the virtuallens 160 as well as the resolution of the image displayed by the virtuallens 160. According to an embodiment, the display engine can providecontrols that comprise soft buttons (buttons or other interfacecomponents drawn on the client device display and selected with thepointing device), hard buttons (keyboard or other buttons or switches),or pointer device controls (e.g., left or right mouse button clicks,mouse button down or up, track wheel controls, track ball controls,touch-sensitive controls, or other pointer device controls). Accordingto an embodiment, the display engine can also be configured to providecontrols that enable a user to freeze the virtual lens at its currentposition (i.e., stop it from tracking the pointing device movement), orunfreeze the virtual lens (resume tracking the pointing devicemovement). According to an embodiment, the display engine can also beconfigured to provide controls that enable a user to turn off thevirtual lens display, such that the full base-resolution image is shownwithout the high resolution overlay, or to turn the virtual lens displayback on. Some controls can perform multiple functions, such as changingboth the virtual lens size and resolution of the image displayed by thevirtual lens 160 together.

The method illustrated in FIG. 3 illustrates the steps taken by theserver 120 that correspond to the steps performed by the client device110 in FIG. 2. The server 120 receives a request for a base-resolutionimage from the client device 110 (step 310). If access is to berestricted, the server 120 can check whether the user or client device110 has access rights to the requested image (step 320) per an accesscontrol policy. According to an embodiment, when access to the image isto be restricted, the request sent by the client device 110 can includeidentification information associated with a user or the client device110 that can be used in determining whether the server 120 should grantaccess to the image content stored on, generated on, or input to theserver 120.

A determination is made whether the user or client device 110 (or both)has access rights for the requested image (step 325). If the user orclient device 110 does not have access to the requested image, theserver 120 can be configured to send a message to the client device 110indicating that the user or client device 110 does not have access tothe requested content (step 360). Otherwise, if the user has access tothe requested image, the server 120 can generate a base-resolution image(step 330) from a high-resolution image of greater than or equalresolution stored on, generated on, or input to the server 120 andassociated with the base resolution image. According to someembodiments, a base-resolution image may have already been generated fora particular high-resolution image. In one embodiment, the server can beconfigured to generate a base-resolution image for each high-resolutionimage that is uploaded, input to, or generated on the server 120. Insome embodiments, the resolution level of the base-resolution image canbe configured based on the attributes of the client device upon whichthe base-resolution image is to be displayed. For example, server 120can be configured to generate base-resolution image that has a lowerresolution for a mobile device, such as a mobile phone, which typicallyhave a smaller sized display while the server 120 may be configured togenerate a base-resolution image that has a comparably higher resolutionfor display on a laptop or desktop computer system that has a largerdisplay area having a higher resolution. The server 120 can then sendthe base-resolution image to the client device 120 via network 130 (step335).

The server 120 can then receive a request from the client device 110 fora full high-resolution image or a portion of the high-resolution imagethat corresponds to an area of interest (step 340). When a portion isrequested, it may be the same size as what will be displayed in thevirtual lens 160 or larger. If access is to be restricted, determinationcan again be made whether the user or client device 110 (or both) hasaccess rights to the image (step 345) per the access control policy. Ifthe user does not have access to the image, the server 120 can beconfigured to send a message to the client device 110 indicating thatthe user does not have access to the requested content (step 360).Otherwise, the server 120 can generate or retrieve from memory ahigh-resolution image or a portion of a high-resolution image thatcorresponds to the area of interest identified in the request (step 350)from an image of greater than or equal resolution generated on, inputto, or stored on the server. In an embodiment, the resolution of thehigh-resolution image can be equal to the maximum resolution of theimage that is stored on, generated on, or input to the server 120 or theresolution of the high-resolution image can be less than the resolutionof the maximum-resolution image stored on, generated on, or input to theserver 120 but greater than the resolution of the base-resolution imagethat was provided to the client in step 335. The server 120 can thentransmit the high-resolution image generated in step 350 to the clientdevice 110 via the network 130 (step 355). According to someembodiments, the request that is received from the client device 110 canspecify a level of resolution to be used for the portion of thehigh-resolution image generated in step 350. For example, an applicationbeing executed on the client device 110 that has requested ahigh-resolution image can include a user interface that include a “zoom”tool that allows the user to select a level of resolution of thehigh-resolution image to be displayed in the virtual lens 160. In someembodiments, server 120 can cache the high-resolution images that aregenerated in response to client requests so that the server 120 does nothave to generate the high-resolution image again if another request isreceived for that image at that resolution level in the future.

According to some embodiments, various optimizations can be provided forthe successive download method. For example, in some embodiments, imagesof multiple resolutions can be preloaded by the client device inanticipation of the user requesting to view those images. In anotherembodiment, images at different resolutions that the client hasdownloaded may be cached in memory. According to another embodiment, theclient device 110 can be configured to request and the server 120 can beconfigured to transmit only that portion of a high-resolution image thatwill be displayed in the virtual lens, or a region from ahigh-resolution image containing the area to be displayed within thevirtual lens, rather than the full high-resolution image. In oneexample, this approach can be used if the transmission times for thefull high-resolution image are too high or if the user is expected toview only a subset of the image at high resolution.

In some embodiments, the resolution level of the base-resolution imagecan be determined based on the attributes of the client device 110 uponwhich the base-resolution image is to be displayed and the bandwidth anddelay characteristics of the network 130 connecting the client device110 and the server 120. For example, server 120 can be configured togenerate base-resolution image that has a lower resolution for a mobiledevice, such as a mobile phone, which typically have a smaller sizeddisplay while the server 120 may be configured to generate abase-resolution image that has a comparably higher resolution fordisplay on a laptop or desktop computer system that has a larger displayarea having a higher resolution. In an embodiment, the resolution levelof the high-resolution images corresponding to the base-resolution imagecan also be adjusted based on the attributes of the client device 110,the server 120, and the network 130.

Client Downscaling Method

FIGS. 5 and 6 are flow diagrams of a client downscaling method that canbe used in conjunction with an image viewing system 100 according to anembodiment. FIG. 5 illustrates the steps of the method that can beperformed at client device 110 according to one embodiment, and FIG. 6illustrates the steps of a method that can be performed by server 120.

The method of FIG. 5 begins when a client device 110 receives a requestto view an image at the client device (step 510). The client device 110sends a request to the server 120 for a top-resolution image (step 520)that corresponds to the image that was requested, where the requestedtop resolution is less than or equal to the maximum resolution at whichthe image is generated on, input to, or stored in memory on the server120. According to an embodiment a display engine module can beimplemented on the client device 110 that is configured to processrequests for images from applications on the client device 110 and tosend a request via network 130 to the server 120 for a top-resolutionimage that corresponds to the requested image.

A determination is made whether the top-resolution image was receivedfrom the server 120 (step 525). According to an embodiment, if access tothe image is to be restricted, the server 120 can make a determinationwhether the user of the client device or client device 110 (or both) isauthorized to view the image content requested per the access controlpolicy. According to an embodiment, the request sent by the clientdevice 110 can include identification information associated with a useror the client device 110 that can be used to determine whether theserver 120 should grant access to the image content stored on, generatedon, or input to the server 120. If the user or client device 110 is notauthorized to access the requested image, the server 120 can optionallysend a message to the client device 110 indicating that the user orclient device 110 is not authorized to access the requested image.According to an embodiment, the client device 110 can also be configuredkeep track of how much time has passed since the request was transmittedto the server 120 and to timeout the request if the top-resolution imageis not received within a predetermined amount of time.

If the image is not received from the server 120, the client device 110can optionally display a message to the user indicating that therequested image could not be accessed (step 560). According to someembodiments, a detailed error message can be generated that describeswhy the image could not be accessed. For example, the message canindicate that the request timed out if a response was not receivedwithin a predetermined amount of time, or that the user was notauthorized to view the requested content.

If the image is received by the client device 110 from the server 120,the client device 110 can generate a base-resolution image (step 530)from the top-resolution image received from the server 120. According toan embodiment, the display engine of the client device 110 can beconfigured to scale down the top-resolution image upon receipt of theimage from the server 120. According to an embodiment, the displayengine can be configured to scale down the top-resolution image based onthe available display space.

According to some embodiments, a base-resolution image may have alreadybeen generated by the client device 110 for a particular top-resolutionimage that was previously received from server 120. In some embodiments,the resolution level of the top-resolution image can be configured basedon the attributes of the client device upon which the image is to bedisplayed and/or the bandwidth and delay characteristics of the network130 connecting the client device 110 and the server 120. For example,server 120 can be configured to generate a top-resolution image that hasa lower resolution for a mobile device, such as a mobile phone, whichtypically have a smaller sized display while the server 120 may beconfigured to generate a top-resolution image that has a comparablyhigher resolution for display on a laptop or desktop computer systemthat has a larger display area having a higher resolution.

The client device 110 can display the base-resolution image in displayregion 150 of the client device 110 (step 533). According to anembodiment, the display engine of the client device can be configured toadjust the size of the base-resolution image based on the availablespace on the display area of the client device 110 for displaying thebase-resolution image. The client device 110 can then receive a requestfrom the user to view an area of interest of the image in highresolution (step 535). According to an embodiment, the user can use aninput device, such as a pointing device, including a mouse, touch pad,touch screen, joystick, track ball, arrow keys, buttons or other inputdevice that allows the user to select an area of interest within thebase-resolution image that the user would like to view in highresolution. According to an embodiment, the client device 110 canprovide a user interface where the user can drag or move a cursor or ashape, such as a rectangle or oval, to the location of the area ofinterest on the base-resolution image.

The client device 100 can then generate a high-resolution image thatcorresponds to the area of interest identified by the user (step 540).The client device can generate the high-resolution image from thetop-resolution image that was received from the server 120. According toan embodiment, when the user requests to view an area of interest withinthe image at a high resolution (higher than the resolution of thebase-resolution image), the client device 110 can scale down thetop-resolution image to a high-resolution image of higher resolutionthan the base resolution (e.g., 1080×810 for a 720×540 base resolution)and display the portion of the high-resolution image in the virtual lens160 corresponding to the area of interest selected by the user (step555). The virtual lens 160 overlays the area of interest in theunderlying base-resolution image. According to an embodiment, if theuser requests a still higher resolution image, the display enginegenerates another high-resolution image of higher resolution than theprevious high-resolution image of a resolution up to and including thetop resolution received from server 120, and displays a portion of thathigh-resolution image in the virtual lens 160 corresponding to theuser-selected area of interest. Once again, the virtual lens 160 can beoverlaid on the area of interest in the underlying base-resolutionimage. Further, in some embodiments, the display engine module can beconfigured to provide a user interface that allows a user to requestchanges in the virtual lens size as well as in the resolution of theimage displayed by the virtual lens 160.

The method illustrated in FIG. 6 illustrates the steps taken by theserver 120 that correspond to the steps performed by the client device110 in FIG. 5. The server 120 receives a request for a top-resolutionimage from the client device 110 (step 610). If access to the image isto be restricted, the server 120 can check whether the user or clientdevice 110 has access rights to the requested image (step 620) per anaccess control policy. According to an embodiment, the request sent bythe client device 110 can include identification information associatedwith a user or the client device 110 that can be used in determiningwhether the server 120 should grant access to the image content storedon, generated on, or input to the server 120.

A determination is made whether the user or client device 110 has accessrights for the requested image (step 625). If the user does not haveaccess rights for the requested image, the server 120 can optionally beconfigured to send a message to the client device 110 indicating thatthe user or client device 110 does not have access to the requestedcontent (step 660). Otherwise, if the user has access to the requestedimage, the server 120 can generate a top-resolution image from anassociated high-resolution image of greater than or equal resolutionthat was generated on, input to, or stored on the server 120, andtransmit the top-resolution image to the client device 110 via thenetwork 130 (step 630).

Various optimizations may be provided for the client downscaling method,including preloading the top-resolution images on the client device 110in anticipation of the user requesting to view these images (e.g., ifthe image is the next in a series of different images to be viewed).

The client downscaling method can be used in conjunction with thesuccessive download method. For example, in one embodiment, for up to aparticular resolution, the client downscaling method could be used. Forrequests for high-resolution images above that resolution threshold, thesuccessive download method can be used. In this case, the top-resolutionimage downloaded for the client downscaling method can be of lowerresolution than the maximum available on the server. Alternatively, thesuccessive download method can be used up to a particular resolution,and the client downscaling method used above the predeterminedresolution threshold. In some embodiments, a combination of the twomethods can be used to optimize various performance parameters forcertain usage scenarios.

Server Composition Method

FIGS. 7 and 8 are flow diagrams of a server composition method that canbe used in conjunction with an image viewing system 100 according to anembodiment. FIG. 7 illustrates the steps of the method that can beperformed at client device 110 according to one embodiment, and FIG. 8illustrates the steps of a method that can be performed by server 120.

The method of FIG. 7 begins when a client device 110 receives a requestto view an image at the client device (step 710). According to anembodiment, the request can comprise a user accessing a document orimage from an application. In other embodiments, the request cancomprise a user accessing a particular web page or other content from abrowser application running on the client device 110. In yet anotherembodiment, the request can comprise a user executing an application onthe client device 110 that uses high-resolution image content retrievedfrom the server 120.

In the example of FIG. 7, the client device 110 sends a request to theserver 120 for a base-resolution image (step 720) that corresponds tothe image that was requested. According to an embodiment, a displayengine module can be implemented on the client device 110 that isconfigured to process requests for images from applications on theclient device 110 and to send a request via network 130 to the server120 for a base-resolution image that corresponds to the requested image.

A determination is made whether the image was received from the server120 (step 725). According to an embodiment, if access to the image is tobe restricted, the server 120 can make a determination whether the userof the client device or client device 110 (or both) is authorized toview the image content requested per the access control policy.According to an embodiment, the request sent by the client device 110can include identification information associated with a user or theclient device 110 that can be used in determining whether the server 120should grant access to the image content stored on, generated on, orinput to the server 120. If the user is not authorized to access therequested image, the server 120 can optionally send a message to theclient device 110 indicating that the user or client device 110 is notauthorized to access the requested image. According to an embodiment,the client device 110 can also be configured to keep track of how muchtime has passed since the request was transmitted to the server 120 andto timeout the request if the base-resolution image is not receivedwithin a predetermined amount of time.

If the image is not received from the server 120, the client device 110can optionally display a message to the user indicating that therequested image could not be accessed (step 760). According to someembodiments, a detailed error message can be generated that describeswhy the image could not be accessed. For example, the message canindicate that the request timed out if a response was not receivedwithin a predetermined amount of time, or that the user was notauthorized to view the requested content.

If the image is received by the client device 110 from the server 120,the client device 110 can display the base-resolution image in displayregion 150 of the client device 110 (step 730). According to anembodiment, the display engine of the client device can be configured toadjust the size of the base-resolution image based on the availablespace on the display area of the client device 110 for displaying thebase-resolution image.

The client device 110 can then receive a request from the user to viewan area of interest of the image in high resolution (step 735).According to an embodiment, the user can use an input device, such as apointing device, including a mouse, touch screen, touchpad, joystick,trackball, arrow keys, buttons, or other input device that allows theuser to select an area of interest within the base-resolution image thatthe user would like to view in high resolution.

The client device can then send a request to the server 120 for acomposed image comprised of the base-resolution image overlaid at thearea of interest with a virtual lens showing the area of interest inhigh-resolution image (step 740). According to an embodiment, therequest can include the coordinates of the area of interest relative toa reference point on the image, the desired resolution level for thehigh-resolution image, and the virtual lens size and shape. The desiredresolution can fall into a range above the resolution of thebase-resolution image and up to the resolution of the maximum-resolutionimage stored on, generated on, or input to the server 120. One or moreareas of interest may be specified, each at a specified position,resolution, and virtual lens size and shape.

According to an embodiment, the request can include a set of coordinatesrelative to a reference point on the base-resolution image thatcorrespond to the area of interest. For example, in some embodiments,the client device 110 is configured so that a user can draw a rectangleon the base-resolution image to indicate the area of interest that theuser would like to see in high resolution, and coordinates of theleft-top and right-bottom corners of the rectangle, or the coordinatesof the left-top and the width and height of the rectangle, can beprovided to the server 120 in the request for the high-resolution image.According to an embodiment, the display engine module can be configuredto translate screen coordinates to pixel coordinates on thebase-resolution image, and the request to the server for thehigh-resolution image can include the pixel coordinates of the area ofinterest specified by the user. According to an alternative embodiment,the client device 110 can provide a user interface where the user candrag or move a cursor or shape, such as a rectangle or oval, to thelocation of an area of interest on the base-resolution image in order toreceive a high-resolution image that corresponds to the area indicatedby the cursor or covered by the shape.

A determination is made whether the composed image was received from theserver 120 (step 745). If the image is not received from the server 120,the client device 110 can optionally display a message to the userindicating that the requested image could not be accessed. Otherwise, ifthe requested composed image is received by the client device 110, theclient device 110 can replace the high-resolution image in displayregion 150 with the composed image (step 755).

According to an alternative embodiment, in order to improve responsetime, the composed image can be downloaded from the server 120 inadvance of a user's request to view the portion of the high-resolutionimage in the virtual lens 160. In such an embodiment, the composed imageis not displayed until such display is requested by the user. Accordingto an embodiment, the pre-fetch of the composed image can be initiatedby some user action, which can trigger the client device 110 to send arequest the server 120 for the composed image. For example, in someembodiments, the download of the composed image can be requested at thetime the base-resolution image is requested from the server 120, orshortly after the base-resolution image is received from the server.Such requests can be sent if the area of interest can be determined inadvance of the user actually requesting that portion of the image. Forexample, when a route on a map is displayed, the areas of interest maybe the origin and destination. More than one such image can bepre-fetched for different areas of interest or different high resolutionlevels. Alternatively, in other embodiments, the client device 110 canbe configured to initiate the download of the composed image with ananticipated area of interest and initial high resolution level inresponse to the user depressing a soft or hard key (e.g., an “imageviewing system activate” button) or by clicking on a pointing devicebutton or other button or key. Continuing this pre-loading technique, asubsequent download of the composed image with the next higherresolution displayed in the virtual lens can be requested uponcompletion of each composed image download, up to the maximumresolution.

According to an embodiment, the client device 110 can be configured toallow the user to move the virtual lens 160 over the base-resolutionimage in display region 150. In one embodiment, the client device 110 isconfigured such that the user can move the virtual lens using a pointingdevice, such as mouse, touchpad, touch screen, joystick, trackball,arrow keys, or buttons. In an embodiment, the display engine module ofthe client device 110 is configured to request from the server 120 inreal time, as the user moves the cursor across the base-resolutionimage, the composed image for the area of interest indicated by thecurrent cursor position relative to a reference point on thebase-resolution image, at the same resolution level and virtual lenssize and shape. When the new composed image is received, the clientdevice 110 can display the new composed image in place of the previouslyreceived composed image. With the server composition method, the abilityto track the cursor movement and change the area of interest and virtuallens location and contents accordingly relies on a high bandwidth, lowlatency network 130 and a responsive server 120. According to anembodiment, the display engine takes into account the cursor positionwithin the base-resolution image relative to a point of reference, suchas the left-top corner of the image, to determine the coordinates of thearea of interest. In an embodiment, the display engine module can alsotake into account whether the user has scrolled the display on theclient device display and adjust for horizontal or vertical scrollingamounts (or both).

According to an embodiment, the display engine module of the clientdevice 110 can be configured to allow a user to request a change in thelevel of resolution of the high-resolution image displayed in thevirtual lens 160. According to an embodiment, the display engine modulecan be configured to provide user interface controls, such as softbuttons, sliders, pointer device controls, or other types of interfacecomponents with which the user can interact to select a desired level ofresolution for the high-resolution image displayed in the virtual lens160. In an embodiment, the user can select a level of resolution for theimage displayed in the virtual lens 160 that is up to the maximumresolution level of the image stored on, generated on, or input to theserver 120. In an embodiment, the user can select a level of resolutionthat is up to the maximum resolution and greater than the resolution ofthe base-resolution image.

In response to a request to change the resolution of the portion of theimage displayed by the virtual lens 160, the display engine module canbe configured to send a request to the server 120 for the composed imagecomprised of the base-resolution image overlaid at the area of interestwith a virtual lens containing the portion of the high-resolution imagecorresponding to the area of interest at the selected resolution level.

According to an embodiment, the display engine of the client device 110can also be configured to allow a user to change the size of the virtuallens 160 as well as the resolution of the image displayed by the virtuallens 160. According to an embodiment, the display engine can providecontrols that comprise soft buttons (buttons or other interfacecomponents drawn on the client device display and selected with thepointing device), hard buttons (keyboard or other buttons or switches),or pointer device controls (e.g., left or right mouse button clicks,mouse button down or up, track wheel controls, track ball controls,touch-sensitive controls, or other pointer device controls). Accordingto an embodiment, the display engine can also be configured to providecontrols that enable a user to freeze the virtual lens at its currentposition (i.e., stop it from tracking the pointing device movement), orunfreeze the virtual lens (resume tracking the pointing devicemovement). According to an embodiment, the display engine can also beconfigured to provide controls that enable a user to turn off thevirtual lens display, such that the full base-resolution image is shownwithout the high resolution overlay, or to turn the virtual lens displayback on. Some controls can perform multiple functions, such as changingboth the virtual lens size and resolution of the image displayed by thevirtual lens 160. For any change to the virtual lens 160 size orposition, or change to whether the virtual lens 160 is shown or hidden,the client device 110 can send a request to the server 120 for newcomposed image, unless a matching composed image is already in clientdevice's 100 memory. When the composed image is received, client device110 can display the composed image in place of the previous composedimage.

The method illustrated in FIG. 8 shows the steps taken by the server 120that correspond to the steps performed by the client device 110 in FIG.7. The server 120 receives a request for a base-resolution image fromthe client device 110 (step 810). If access is to be restricted, theserver 120 can check whether the user or client device 110 (or both) hasaccess rights to the requested image (step 820) per an access controlpolicy. According to an embodiment, the request sent by the clientdevice 110 can include identification information associated with a useror the client device 110 that can be used in determining whether theserver 120 should grant access to the image content stored on, generatedon, or input to the server 120.

A determination is made whether the user has access rights for therequested image (step 825). If the user does not have access to therequested image, the server 120 can be configured to send a message tothe client device 110 indicating that the user does not have access tothe requested content (step 860). Otherwise, if the user or clientdevice 110 has access to the requested image, the server 120 cangenerate a base-resolution image (step 830) from the high-resolutionimage stored on, generated on, or input to the server 120. According tosome embodiments, a base-resolution image may have already beengenerated for a particular high-resolution image. In one embodiment, theserver can be configured to generate a base-resolution image for eachhigh-resolution image that is uploaded, input to, or generated on theserver 120. In some embodiments, the resolution level of thebase-resolution image can be configured based on the attributes of theclient device upon which the base-resolution image is to be displayed.For example, server 120 can be configured to generate base-resolutionimage that has a lower resolution for a mobile device, such as a mobilephone, which typically have a smaller sized display while the server 120may be configured to generate a base-resolution image that has acomparably higher resolution for display on a laptop computer systemthat has a larger display area having a higher resolution. The server120 can then send the base-resolution image to the client device 120 vianetwork 130 (step 835).

The server 120 can then receive a request from the client device 110 fora composed image, including the coordinates of the area of interest,resolution levels of the base-resolution image and high-resolutionoverlay, and virtual lens size and shape (step 840). If access is to berestricted, determination can again be made whether the user or clientdevice 110 has access rights to the image (step 845) per the accesscontrol policy. If the user does not have access to the image, theserver 120 can be configured to send a message to the client device 110indicating that the user does not have access to the requested content(step 860). Otherwise, the server 120 can generate or retrieve frommemory a composed image comprised of the base-resolution image overlaidat the area of interest with a virtual lens containing the portion of ahigh-resolution image that corresponds to the area of interestidentified in the request (step 850). In an embodiment, the resolutionof the high-resolution image can be equal to the maximum resolution ofthe image that is stored on, generated on, or input to the server 120 orthe resolution of the high-resolution image can be less than theresolution of the maximum-resolution image stored on, generated on, orinput to the server 120 but greater than the resolution of thebase-resolution image that was provided to the client in step 835. Theserver 120 can then transmit the composed image generated in step 850 tothe client device 110 via the network 130 (step 855). According to someembodiments, the request that is received from the client device 110 canspecify a level of resolution to be used for the portion of thehigh-resolution image generated in step 350. For example, an applicationbeing executed on the client device 110 that has requested ahigh-resolution image can include a user interface that include a “zoom”tool that allows the user to select a level of resolution of thehigh-resolution image to be displayed in the virtual lens 160. In someembodiments, server 120 can cache the composed images that are generatedin response to client requests so that the server 120 does not have togenerate the composed image again if another request is received forthat image at that resolution level in the future.

According to some embodiments, various optimizations can be provided forthe server composition method. For example, in some embodiments,composed images can be preloaded by the client device in anticipation ofthe user requesting to view those images. In some embodiments, theresolution level of the base-resolution image can be configured based onthe attributes of the client device 110 upon which the base-resolutionimage is to be displayed and the bandwidth and delay characteristics ofthe network 130 connecting the client device 110 and the server 120. Forexample, server 120 can be configured to generate a base-resolutionimage that has a lower resolution for a mobile device, such as a mobilephone, which typically have a smaller sized display while the server 120may be configured to generate a base-resolution image that has acomparably higher resolution for display on a laptop computer systemthat has a larger display area having a higher resolution. Theresolution level of the high-resolution images corresponding to thebase-resolution image may also be adjusted based on the attributes ofthe client device 110.

Collaborative Method

According to another embodiment, the image viewing system 100 can beconfigured to allow a first user to select an area of interest,resolution, and virtual lens shape and size on behalf of a second useror users. This technique can be employed, for example, in collaborativeor instructional applications. In an embodiment, the first user'sselection is saved for later use when the second user requests theimage. The selection parameters can be communicated to the client device110 of the second user for use in sending a request for the image to theserver, or can be saved on the server 120 for use when the second userrequests the image. With this technique, the second user can bypass thesteps of selecting the area of interest, virtual lens size and shape,and resolution level of the high-resolution image displayed in thevirtual lens since the selection has already been done by the firstuser. In an embodiment, this technique can be used in combination witheither the successive download method, the client downscaling method, orthe server composition method. Either of these methods can be used bythe first user in specifying the selection parameters to be used by thesecond user. In another embodiment, the first user can enter theselection parameters via the client device, for example, using a menu orcommand. In an embodiment, either the successive download method, theclient downscaling method, or the server composition method can be usedby the second user, with the steps of selecting the area of interest,virtual lens size and shape, and resolution level of the high-resolutionimage replaced by the steps of retrieving or determining the selectionparameters. Subsequently, the methods of the successive download method,the client downscaling method, or the server composition method can beused to, for example, move the virtual lens or change the virtual lenssize and shape, or change the resolution of the high-resolution imagedisplayed in the virtual lens. In an embodiment, collaboration can bedone in real time, with the first user, for example, moving the virtuallens for the second user, or changing the resolution of the imagedisplayed in the virtual lens for the second user, or changing thesecond user's virtual lens size or shape.

FIGS. 9A and 9B are flow diagrams of a collaborative method that can beimplemented on client devices of the image viewing system illustrated inFIG. 1 according to an embodiment. FIG. 9A illustrates a method forspecifying a set of selection parameters for displaying an image to asecond user according to an embodiment. The selection parameters caninclude an area of interest, resolution specification, a virtual lensspecification, other display parameters, or a combination thereof. Theresolution specification can include the resolution of thebase-resolution image and the resolution of the high-resolution image,or the ratio of the high resolution over the base resolution, orequivalent. A ratio can be used to enable the first user's client deviceand second user's client device to display the base-resolution image atdifferent resolutions (e.g., when the displays are different sizes), andto display the portion of the high-resolution image on the second user'sclient device such that the proportional resolution increase of thehigh-resolution image over the base-resolution image matches that usedby the first user. The virtual lens specification comprises a virtuallens shape and either a virtual lens absolute size or size relative tothe size of the base resolution image.

A first user specifies the selection parameters to be used by theviewing system 100 for displaying an image to a second user (step 910).The first user can then transfer the selection parameters to the seconduser (step 920). According to an embodiment, the first user can transmitthe selection parameters from the first user's client device 110 to thesecond user's client device 110. For example, for a web application, thefirst user can send the parameters in an email message that includes aUniform Resource Locator (URL) link that includes the selectionparameters in the query string. When the link is clicked by the seconduser, the email client in the second user's client device 110 passes thelink to a browser, which can then request the web page that contains thelogic to request the images specified in the selection parameters fromthe server 120 and render them on the second user's client device'sdisplay, with a portion of the high-resolution image corresponding tospecified the area of interest displayed at the specified resolution ina virtual lens of the specified size and shape, overlaid over thebase-resolution image at the area of interest. In an alternativeembodiment, a first application running in the first user's clientdevice 110 may transmit the selection parameters to a second applicationrunning in the second user's client device 110. In an alternativeembodiment, an application running in the first user's client device 110may transmit the selection parameters to the server 120 for retrievaland use by an application running on the second user's client device110. In an alternative embodiment, the selection parameters can becomputed by algorithms executing on either the first user's clientdevice, second user's client device, or the server. The algorithms maybe used in combination with user input. As an example embodiment, formapping applications, an algorithm may locate a specific location on amap such as an origin or destination of a route. An algorithm can alsopermit a route to be traced in high resolution over a period of time orin response to user input. As another example, for a video, algorithmscan be used to track a moving object over time in high resolution in thecontext of the base-resolution surroundings. The initial location of orcharacteristics of the object can be specified by the user.

FIG. 9B illustrates a method for receiving a set of selection parametersfor displaying an image and requesting the image from the server 120according to an embodiment. Client device 110 receives from the seconduser a request to view the image corresponding to the selectionparameters (step 930). The second user can specify that the selectionparameters be used in displaying the requested image, or logic executingon the second user's client device 110 can automatically determine thatthere are selection parameters for the image and process the image fordisplay accordingly. The determination as to whether there are selectionparameters can be performed either by whether the selection parametershave been received from the first user's client device, by querying theserver for the selection parameters over the network, or by whetherthere is an algorithm that can be used on the second user's clientdevice for generating them. The client device 110 then sends a requestto the server 120 for the requested image (step 935). The requestincludes some or all of the selection parameters, depending on themethod used. In an embodiment, for the successive download method, theclient device 110 sends either separate requests or a combined requestto the server 120 for the base-resolution image and the high-resolutionimage (or portion of the high resolution image). The client device 110can determine the base resolution and high resolution levels from theselection parameters and the available display space on the clientdevice's 110 display and the network 130 capabilities. When requesting aportion of the high-resolution image, the client device 110 includes theset of coordinates of a point or object in the area of interest relativeto a reference point in the image, the resolution level of thehigh-resolution image, and the size and shape of the portion of thehigh-resolution image being requested. These parameters are derived fromthe selection parameters, possibly adjusted for the capabilities of thesecond user's client device 110 or the network 130 connecting the seconduser's client device 110 and the server 120. In an alternativeembodiment, for the client downscaling method, the client device 110sends a request to the server 120 for the top-resolution image. The topresolution level can be determined from the selection parameters and thecapabilities of the client device 110 and the network 130. In analternative embodiment, for the server composition method, the clientdevice 110 sends to server 120 a request that includes the baseresolution level, the high resolution level, the area of interestcoordinates relative to a reference point, and virtual lens size andshape, all determined from the selection parameters and possiblymodified to take into account the capabilities of the client device 110and network 130.

A determination is made whether the requested image was received fromthe server 120 (step 945). According to an embodiment, if access to theimage is to be restricted, the server 120 can make a determinationwhether the user of the client device or client device 110 (or both) isauthorized to view the image content requested per the access controlpolicy. According to an embodiment, the request sent by the clientdevice 110 can include identification information associated with a useror the client device 110 that can be used to determine whether theserver 120 should grant access to the image content stored on, generatedon, or input to the server 120. If the user is not authorized to accessthe requested image, the server 120 can optionally send a message to theclient device 110 indicating that the user or client device 110 is notauthorized to access the requested image. According to an embodiment,the client device 110 can also be configured keep track of how much timehas passed since the request was transmitted to the server 120 and totimeout the request if the requested image is not received within apredetermined amount of time.

If the image is not received from the server 120, the client device 110can optionally display a message to the user indicating that therequested image could not be accessed (step 960). According to someembodiments, a detailed error message can be generated that describeswhy the image could not be accessed. For example, the message canindicate that the request timed out if a response was not receivedwithin a predetermined amount of time, or that the user was notauthorized to view the requested content.

If the requested image or images are received by the client device 110from the server 120, the client device 110 can display the requestedimage (step 950) using the selection parameters provided by the firstuser or algorithms. In an embodiment, when the second user is using thesuccessive download method, client device 110 can receive abase-resolution image and a high-resolution image from the server 120.The client device 110 can display the base-resolution image overlaidwith a portion of the high-resolution image corresponding to the area ofinterest at a location corresponding to the area of interest. In anembodiment, when the second user is using the client downscaling method,the client device 110 can receive the top-resolution image and use it togenerate a base-resolution image and a high-resolution image. The clientdevice 110 can then display the base-resolution image overlaid with theportion of the high-resolution image corresponding to the area ofinterest at a location corresponding to the area of interest. In anembodiment, when the second user is using the server composition method,the client device 110 can receive a composed image and display it.

FIG. 10 is a flow diagram of a collaborative method that can beimplemented on a server of the image viewing system illustrated in FIG.1 according to an embodiment. The method illustrated in FIG. 10illustrates the steps taken by the server 120 that correspond to thesteps performed by the client device 110 in FIGS. 9A and 9B. The server120 receives a request for a an image from the second user's clientdevice 110 per the selection parameters (step 1010). If access to theimage is to be restricted, the server 120 can check whether the seconduser or client device 110 has access rights to the requested image (step1020) per an access control policy. According to an embodiment, therequest sent by the client device 110 can include identificationinformation associated with a user or the client device 110 that can beused in determining whether the server 120 should grant access to theimage content stored on, generated on, or input to the server 120.

A determination is made whether the user or client device 110 (or both)has access rights for the requested image (step 1025) per an accesscontrol policy. If the user or client device 110 does not have accessrights for the requested image, the server 120 can optionally beconfigured to send a message to the client device 110 indicating thatthe user does not have access to the requested content (step 1060).Otherwise, if the user has access to the requested image, the server 120can generate the requested image or images based on the selectionparameters (step 1030), and transmit them to the client device 110 viathe network 130 (step 1035). In an embodiment, for the successivedownload method, the request can be for a base-resolution image, ahigh-resolution image or a portion of the high-resolution image, or botha base-resolution image and a high-resolution image or a portionthereof. The server 120 can generate and transmit the requested imagesto the client device 110. In an alternative embodiment, for the clientdownscaling method, the request can be for a top-resolution image, andthe server 120 can generate and transmit to the client device 110 thetop-resolution image of a resolution less that or equal to maximumresolution generated on, input to, or stored on the server 120. In analternative embodiment, for the server composition method, the requestcan include selection parameters possibly adjusted to reflect thecapabilities of the client device 110 and network 130, and the server120 can compose an image per the selection parameters and transmit it tothe client device 110.

According to another embodiment, the area of interest and otherselection parameters may be selected for a user by an algorithm oralgorithms executing on either the client device 110 or server 120.Examples include, for maps, the origin or destination of a route and,for medical images, a specific anatomical feature or abnormality.

Additional Methods

Other additional methods can optionally be used in combination with theSuccessive Download Method, the Client Downscaling Method, the ServerComposition Method, and the Collaborative Method described above. Someexamples of these methods are described below.

According to an embodiment, a method for preventing the virtual lens 160from extending over the border of the base-resolution image is provided.In the methods described above, the display engine module of the clientdevice 110 centers the virtual lens and the portion of thehigh-resolution image that is displayed by the virtual lens over thearea of interest in the base-resolution image selected forhigh-resolution display. In an embodiment, the display engine module ofthe client device 110 can be configured to determine whether the virtuallens 160 would extend over the border of the base-resolution image andto offset the position of the virtual lens and the high-resolution imagedisplayed by the virtual lens by the amount that the virtual lens wouldextend over the border of the base-resolution image. In one embodiment,the display engine of the client device 110 can adjust the size andshape of the virtual lens and offset the position of the virtual lens160 in order to improve the function of an application in which thevirtual lens 160 is being used. For example, the virtual lens can bepositioned over an underlying newspaper or journal column in anelectronic reader application, and the display engine can be configuredto keep the virtual lens 160 centered over the column as long as theuser keeps the pointer/cursor somewhere within the column.

According to another embodiment, the virtual lens can have a border,demarcating the virtual lens from the underlying base-resolution image.The types of border can include a line of various styles, thicknessesand colors, multiple lines of various styles, thicknesses and colors, abevel, or other type of edge. As an alternative type of border for thevirtual lens, the portion of the image at the edges of the virtual lenscan be reduced in size and resolution such that the transition betweenthe high resolution image displayed in the virtual lens and the baseresolution image is smoother and there is less loss or no loss of aportion of the image due to the size differences between thehigh-resolution and base-resolution images. In such an embodiment, thevirtual lens can appear as a type of bubble or raised area over thebase-resolution image, the bubble or raised area having a relativelyflat center section and edges curved in the third dimension (above theimage). Some curvature distortion of the image would appear in theportions curved in the third dimension.

According to another embodiment, the display engine can be configured tofreeze, upon user request, the position of and area of interestdisplayed in high resolution within the virtual lens 160, such that thevirtual lens does not automatically track the movement of the pointingdevice. The display engine can also be configured to unfreeze thevirtual lens 160 upon user request, such that the virtual lens positionand contents automatically track the movement of pointing device.

According to another embodiment, the display engine can be configured toincrease or decrease the size of the virtual lens 160, to change theshape, dimensions, or border of the virtual lens, change the accessoriesdisplayed with the virtual lens, increase the resolution of the imagedisplayed by the virtual lens 160 up to the maximum resolution storedon, generated on, or input to the server, decrease the resolutiondisplayed within the virtual lens down to but not including the baseresolution, or a combination thereof. When the virtual lens size isincreased or shape is changed, if the portion of the high-resolutionimage that is in the client device's 110 memory is insufficient to fillthe virtual lens, the client device 110 can request from the server 120a portion of the high-resolution image that is sufficiently large.

The display engine can also be configured to change both the resolutiondisplayed within the virtual lens and the virtual lens size togetherupon user request. Further, the display engine can be configured to,upon user request, hide the virtual lens or show a previously hiddenvirtual lens. Additionally, for example, for video images or otherimages changing in time, the display engine can be configured to changethe image displayed at base resolution in time according to the framerate of the video content or the image changes of the time-changingcontent and to change the image displayed at high resolution in thevirtual lens to be synchronized with the changing base-resolution image.In an embodiment, the frame rates and the current displayed frames ofthe base resolution video content and the high-resolution video contentdisplayed in the virtual lens can be synchronized so that the virtuallens displays a high-resolution portion of the video content that issynchronized with the base resolution video content.

According to another embodiment, the image viewing system 100 can beconfigured to save a user's selection of area of interest for an image,the virtual lens shape and size, and the resolution displayed in thevirtual lens. These parameters may be saved for a user either on theserver 120 or the client device 110 for later retrieval and use.

Methods can be used to handle various performance situations or timingconditions. The display engine can be configured to provide anindication to the user in the situation that the high-resolution imageto be displayed within the virtual lens has not completed downloadingfrom the server over the network. Additionally, the display engine canbe configured to internally represent the display in planes, with thevirtual lens on top of the base image, and to compute the image to bedisplayed from these planes. For example, the display engine module canbe configured to insert, when the virtual lens is not hidden, anadditional opaque plane between the virtual lens and the underlying baseimage. This opaque plane can be of size and shape equal to the virtuallens and positioned immediately below the virtual lens. The displayengine module can be configured to render the opaque plane as visiblewhile there is no image to display in the virtual lens' plane, forexample, when the high-resolution image has not completed downloadingfrom the server.

According to an embodiment, the image viewing system 100 is capable ofsupporting a plurality of images. The image viewing system 100 can beconfigured to support a plurality of client devices 110 and clientdevice users, each viewing possibly different images. The image viewingsystem 100 can include a plurality of servers 120. Multiple servers 120can be used for load balancing purposes to increase performance and forfailover in the event that a server fails or network connectivity to aserver is disrupted. The image viewing system 100 can be configured tosupport a plurality of networks 130, for load sharing or failureprotection. The detection of failures and the failover response caneither be performed by the client devices 110, servers 120, or networks130. The image viewing system 100 can be configured to support aplurality of virtual lenses 160 overlaid on the same base-resolutionimage in display region 150. The image viewing system 100 can beconfigured to support a plurality of base resolution images displayed ondifferent regions of the client device's 110 display, each with one ormore virtual lenses 160 overlaid showing an area of interest in highresolution.

According to an embodiment, the image viewing system 100 can employvarious security methods. For example, the image viewing system 100 canbe configured to restrict public access to specified content on theserver 120. As part of the access control enforcement, the server 120can employ methods to authenticate the identity of the client device'suser (e.g., through a logon procedure on client device 110 involving ausername and password, security token, biometrics, asymmetric encryptionmethods, asymmetric encryption with digital certificate methods,symmetric encryption methods, one-way hash methods, or other userauthentication methods), and/or the identity of the client device 110(e.g., through a pass code, asymmetric encryption methods, asymmetricencryption with digital certificate methods, symmetric encryptionmethods, one-way hash methods, or other device authentication method).Whether or not access control enforcement is performed on the clientdevice 110, the client device's 110 user, or both the client device 110and the user is determined from the access control policy for thesystem. Authentication may be performed for a particular viewing sessionwhen a user first invokes the image viewing system 100 or another systeminvokes the image viewing system 100 on the user's behalf. Afterauthentication is performed, the server 120 may assign a sessionidentifier that is to be submitted with requests from the client device110. For example, for a web application, the server can store a sessionidentifier in a client device's 110 browser cookie store, and thebrowser can send the value of this cookie with requests sent to theserver. According to an embodiment, the server can use the authenticatedidentity to verify the rights of the user and/or client device 110 toaccess a requested image. Identification information as well as theimages themselves can be protected when transmitted over the network 130using encryption (e.g. using Transport Layer Security [TLS], InternetProtocol Security [IPSec], or other security protocol or encryptionmethod). In another embodiment, access control can be based on rules fordetermining access rights using information other than user or deviceidentity (e.g., mandatory access control at a network or subnetworklevel).

According to an embodiment, to improve transmission times across thenetwork 130, images can be compressed prior to transmission from theserver 120 over the network 130 and decompressed on the client device110. Compression can also be used to reduce the memory requirements onthe server 120.

According to an embodiment, the display engine on the client device 110can be configured to request an image at a specific resolution inanticipation of a user requesting to view the image at that resolution.Alternatively, the server 120 can be configured to transmit an image ata specific resolution or composition of resolutions to a client device110 without an explicit request from the client device 110 for the imageat the specified resolution or composition of resolutions, or without anexplicit request for an update to an image that changes in time.

Example Embodiment

For illustrative purposes, an example embodiment of the image viewingsystem's successive download method is described below. One skilled inthe art will recognize that there are numerous other ways ofimplementing the methods of this invention.

In this embodiment, the display engine in the client device can becomprised of a browser that renders a web page containing HypertextMarkup Language (HTML) or Extensible HTML (XHTML) elements, CascadingStyle Sheet (CSS) declarations, and JavaScript code, downloaded from aweb server. Other programming languages (e.g., Java, C#) can also beused instead of JavaScript.

In this embodiment, the region 150 of the client device's display inwhich the base-resolution image is displayed can be an HTML div elementwith an id of graphics0. The z-index property of the div element can beset to 0. The region of the display containing the virtual lens 160 canbe a div with an id of graphics2. The z-index property of the virtuallens's div can be set to 2, and the div can have an outset border of 5pixels in width. There is an additional opaque div with an id ofgraphics 1 that lies between the virtual lens and the base-resolutionimage. The z-index property of this addition div can be set to 1, and isthe same dimensions and size as the virtual lens. The graphics 1 div canhave an opaque background (e.g., a black background). A fourth div canalso be positioned over the other three divs, with an id of graphics3.The fourth div can be the same size as the graphics0 div, and can bepositioned exactly on top of graphics0, with a solid border, atransparent background, and null contents. All of these divs can bepositioned using absolute coordinates on the page.

The user of the client device 110 can request to view an image using theuser interface described above. The display engine module receives therequest and can in turn send a request over the network to server 120for the base-resolution image corresponding to the image requested bythe user. Server 120 can authenticate the user to determine whether theuser should have access to the requested content. In an embodiment, ifthe user has previously logged into the server, and the server has set acookie containing a session identifier in the client device's 110browser, the browser can send the session identifier in the cookie tothe server over a TLS encrypted connection. If the user is permittedaccess, server 120 can transmit the base-resolution image to the clientdevice 110, and the display engine module can display thebase-resolution image in the graphics0 div (either in the foreground orin the background).

According to an embodiment, the user can request that the image viewingsystem be activated by clicking on a button displayed on the userinterface of the client device 110. The display engine module can thenestablish a mousemove, mousedown, mouseover, and mouseout event handlers(or comparable touch screen event handlers) for the graphics3 div. Thevirtual lens can be assigned initial rectangular dimensions. The virtuallens width can be initialized to 50% of the width of the graphics0 divand the height can be initialized to 50% of the height of the graphics0div. Code in the client device 110 then sends a request to the serverfor the image at a first high resolution. The server performs the accessrights verification per the access control policy and, if the user ispermitted access, transmits the high-resolution image to the clientdevice 110.

While the high-resolution image is downloading, the display enginemodule can be configured to flash an indicator on the display indicatingthat the high-resolution image is being downloaded from the server. Whenthe download completes, the display engine module can provide anindication to the user that the download is complete and the system isready. Additionally, the display engine can change the cursor toindicate “wait” (e.g., the hour glass on a PC) while the download istaking place, and back to normal after it completes. After the downloadcompletes, the display engine module sends a request to the server 120for the image at the next higher resolution (if there is one) inanticipation of the user requesting to view the next higher resolutionimage.

The user can click on an area of interest in the base image using apointing device to request that a virtual lens containing a portion ofthe image at high resolution be displayed over the area of interest. Thedisplay engine can compute the position on the display where the virtuallens will be placed. In an embodiment, the virtual lens is centered overthe center point of the area of interest, except when such centeringwould make the lens overlap the border of the graphics0 div. In such asituation, the virtual lens can be offset by the amount necessary toprevent such an overlap, making the point that corresponds to the centerof the area of interest offset from the center of the virtual lens. Thedisplay engine module can then compute the position within thehigh-resolution image of the possibly offset area of interest,determining the left-top position within the high-resolution image. Thedisplay engine module puts the additive inverse of these coordinates inthe graphics2 div style background position property. The display enginemodule can also set the left-top position of the graphics2 div to theabsolute position of the virtual lens on the page. The display enginemodule can then load the high-resolution image into the background ofthe graphics2 div. The display engine module can also set the left-topposition of the graphics 1 div to match that of the graphics2 div. Whilethe high-resolution image is loading, the opaque background of graphics1 div will appear at the virtual lens location.

When the user moves the cursor via the pointing device over thegraphics3 div, the mousemove event handler can track the movement andcause both the virtual lens to change position and the portion of thehigh-resolution image shown within the virtual lens to be offset suchthat the point where the cursor is located in the high-resolution imagedisplayed within the virtual lens matches the point in the underlyingbase image at the cursor position.

When the user left clicks on the pointing device, the display engine canfreeze the virtual lens position. A subsequent left click can unfreezethe virtual lens position, and tracking of the cursor position resumes.This can be repeated indefinitely. Alternatively, when the userdepresses the left mouse button, the display engine can unfreeze thevirtual lens and then freeze the virtual lens position when the userreleases the button. Similarly, for a touch screen, the display enginecan unfreeze the virtual lens when the user touches it, and freeze itwhen the user stops touching it.

When the user right clicks on the pointing device, the display enginemodule can increase both the virtual lens size (graphics2 div andgraphics1 div width and height) and the resolution displayed within thevirtual lens. To do so, if the image at the next higher resolution hasnot yet downloaded, the display engine module can send a request for itto the server. Upon receipt of this request, server 120 verifies theaccess rights of the user per the access control policy, and if accessis permitted, transmits the requested image to the client device overthe network. The display engine can display a portion of this image inthe virtual lens corresponding to the area of interest. In someembodiments, to improve performance, the display engine module canrequest the image at the next higher resolution as soon as the downloadof the current high-resolution image completes, so that downloading theimage at the next resolution can overlap the user's inspecting of theimage at the current resolution. If the download has not completed whenthe user requests the resolution, a loading indicator is displayed, thecursor is changed to “wait”, and the opaque background from the graphics1 div can be shown at the virtual lens location. The display enginemodule can keep higher resolution images downloaded for a base image ina cache so that revisiting a resolution can be done withoutre-downloading image data.

The display engine can provide soft buttons on the display selectedusing the pointing device to increase or decrease the lens size(graphics2 div along with the underlying graphics 1 div), increase ordecrease the resolution displayed within the virtual lens, hide thevirtual lens, and show the virtual lens.

The display engine module can automatically deactivate the image viewingsystem and virtual lens display when the user moves to another image oranother activity.

Logical Architecture

FIG. 11 is a block diagram of the logical components of the server 120according to one embodiment. According to an embodiment, the server 120can be used to implement the processes illustrated in FIGS. 3, 6, 8, and10. The server 120 includes a network interface module 1110, an imagemanagement module 1120, an access control module 1130, and a requestprocessing module 1140. The server 120 is also in communication with adata store 1150 that can be used to store image and/or video content forthe server 120. In some embodiments, the data store 1150 can be astorage area that is implemented on the server 120 (as shown), while inother embodiments, the data store 1150 can be implemented on an externalserver or computer system that is in communication with the server 120either directly or indirectly through a wired or wireless networkconnection.

Network interface module 1110 can be configured to receive requests foran image from the client device 110 over the network 130 and to transmitthe requested image to the client device 110 via the network 130. Thenetwork interface module 1110 is configured to route incoming requestsfrom the client device to the request processing module 1140 and toreceive requested images from the request processing module 1140 fortransmission to the client device 110. For the collaborative method,network interface module 1110 can be configured to receive selectionparameters from a first user's client device 110, and store them in thedata store 1150. Network interface module 1110 can also be configured togenerate the selection parameters using algorithms. Network interfacemodule 1110 is further configured to receive a request for selectionparameters from a second user's client device 110, retrieve therequested selection parameters from the data store 1150 or generate themusing algorithms, and send the selection parameters to the second user'sclient device.

Image management module 1120 is configured to receive image managementrequests for an image (or other content, such as video content) storedin the data store 1150, to access the image stored in the data store1150, and to provide the requested image to the requesting module. Theimage management module 1120 is also configured to input an image froman image input device or system 1160 and to store the image in the datastore 1150.

Request processing module 1140 is configured to receive from clientdevice 110 an image request via the network interface module 1110, tosend an image management request to the image management module 1120 toretrieve an image or other content, such as video content, associatedwith the request, generate the requested image, and send the requestedimage to the network interface module 1110 for transmission to theclient device 110. In an embodiment, when the successive download methodis used, the request processing module 1140 can generate a requestedbase-resolution image, high-resolution image, or portion of ahigh-resolution image using an image retrieved from the image managementmodule 1120 having a resolution greater than or equal to the resolutionof the requested image. In an embodiment, when the client downscalingmethod is used, the request processing module 1140 can generate atop-resolution image from an image retrieved from the image managementmodule 1120 having a resolution greater than or equal to the resolutionof the requested top-resolution image. In an embodiment, when the servercomposition method is used, the request processing module 1140 cangenerate a base resolution image as with the successive download method.Request processing module 1140 can generate a composed image by eitherretrieving a base-resolution image and high-resolution image from theimage management module 1120, or retrieving a top-resolution image andgenerating the base-resolution image and high-resolution image from it,and then overlaying a portion of the high-resolution image correspondingto the area of interest at a location in the base image corresponding tothe area of interest. In some embodiments, the request processing module1140 is configured to request verification of access rights of theclient device 110 or the client device's 110 user (or both) from theaccess control module 1130 to determine whether the access is permittedper an access control policy before generating and sending the requestedimage to the network interface module 1110 for transmission to theclient device 110.

Access control module 1130 can be configured to determine, if imageaccess is restricted, whether access to the requested content ispermitted per the access control policy. If access to the image isrestricted, the access control module 1130 can determine whether clientdevice's 110 user or client device 110 (or both) that is requestingaccess to the image has access rights per the access control policy. Ifthe user or device does not have access to the requested image, theauthentication module can optionally generate a message indicating thatthe user or device does not have access to the requested image. Therequest processing module 1140 can send an authorization request to theaccess control module 1130 to determine whether a user or user devicehas access to a requested image, and the access control module 1130 cansend an authorization response to the request processing module 1140that indicates whether the user or client device has access to theimage.

FIG. 12 is a block diagram of the logical components of the clientdevice 110 according to one embodiment. According to an embodiment, theclient device 110 can be used to implement the processes illustrated inFIGS. 2, 5, 7, and 9. The client device 110 includes a network interfacemodule 1210, an image management module 1220, a user interface module1230, and a request processing module 1240. According to someembodiments, the client device 110 can also be in communication with adata store 1250 that can be used to store image and/or video content forthe client device 110. In some embodiments, the data store 1250 can be astorage area that is implemented on the client device 110 (as shown),while in other embodiments, the data store 1250 can be implemented on anexternal server or computer system that is in communication with theclient device 110 either directly or indirectly through a wired orwireless connection.

Network interface module 1210 can be configured to send requests forimagery content from the client device 110 over the network 130 toserver 120 and to receive content and messages sent to the client device110 via the network 130. As described above, the imagery content caninclude still images as well as video content. For the collaborativemethod, network interface module 1210 can be configured to receiveselection parameters set by a first user and transmit them over network130 either to the server 120 for transfer to a second user's clientdevice 110, or directly to the second user's client device 110. Networkinterface module 1210 on the second user's client device 110 can befurther configured to transmit a request for selection parameters toserver 120, and to receive selection parameters either from server 120or the first user's client device.

Image management module 1220 is configured to receive a request for animage at a resolution and return the requested image at the requestedresolution to the requestor. If the image is in data store 1250, theimage management module 1220 retrieves the image from the data store1250 rather than requesting the image from the server 120. If therequested image not in the data store 1250, the image management module1220 sends a request to the network interface module 1210 to betransmitted to the server 120, and receives the image from the networkinterface module 1210 after the image is received from the server 120,and caches the image in the data store 1250. The image management module1220 returns the image to the requesting module.

User interface module 1230 can be configured to accept user inputs frominput device 1270 and display images (and other information) on display1260 as illustrated in FIGS. 1 and 4. The user interface module candisplay a base-resolution image 150 and a virtual lens showing ahigh-resolution image 160 overlaid over the base-resolution image.According to some embodiments, the user interface module 1230 (and someor all of the other modules illustrated in FIG. 12) can comprise aplug-in, software library, service routine, function, process, thread,or device driver that can be executed or invoked by another program,such as a browser application or other application that can be executedon the client device 110. The user interface module 1230 can also inputfrom one or more input devices 1270 such as buttons, keys, pointingdevices or other input devices that allow a user to interact with theimage viewing system. For example, the user interface module 110 canprovide controls that allow a user to select the area of interest, sizeof the virtual lens and/or the resolution of the image displayed by thevirtual lens.

The user interface module 1230 can also be configured to receiverequests for a base-resolution or high-resolution imagery content from auser, and to instruct the request processing module 1240 to retrieve orgenerate the requested image, and display images received from therequest processing module 1240 on display 1260. According to someembodiments, the user interface module 1230 can be configured to sendrequests to the request processing module 1240 for a base-resolutionimage, or to send a request to the request processing module 1240 for acomposed image having a portion of a high-resolution image correspondingto an area of interest overlaid on the base resolution image at alocation the corresponds to the area of interest. The user interfacemodule 1230 displays the user-requested images received from the requestprocessing module on display 1260. For the collaborative method, userinterface module 1230 can send selection parameters set by a first userto the network interface module 1210 for transmission to the server 120for a second user's retrieval, or to the second user's client device 110either directly over the network or through transfer devices.

Request processing module 1240 can be configured to receive a requestfor an image from user interface module 1230. The request can be for abase-resolution image. In an embodiment, if selection parameters havebeen specified by a first user for a second user or generated by analgorithm for a second user, and the image request is from the seconduser, the request processing module 1240 can generate a composed imageper the selection parameters. For a base-resolution image, when thesuccessive download method or server composition method are used, therequest processing module 1240 sends a request for the base-resolutionimage to the image management module 1220, and receives thebase-resolution image from the image management module 1220. When theclient downscaling method is used, the request processing module 1240sends a request to the image management module 1220 for a top-resolutionimage, receives the top resolution image from the image managementmodule 1220, and generates the base-resolution image from the topresolution image. The request processing module 1240 sends thebase-resolution image requested by the user to the user interface module1230 for display on display 1260. For a composed image, when thesuccessive download method is used, the request processing module 1240sends a request for the base-resolution image and the high-resolutionimage or portion of the high-resolution image corresponding to the areaof interest to the image management module 1220. The request processingmodule 1240 receives the requested base-resolution image andhigh-resolution image from the image management module 1220. The requestprocessing module 1240 then generates the user-requested composed image,with a portion of the high-resolution image corresponding to the area ofinterest overlaid on the base-resolution image at a locationcorresponding to the area of interest. When the client downscalingmethod is used, the request processing module 1240 requests atop-resolution image from the image management module 1220. Uponreceiving the top-resolution image, the request processing modulegenerates a base-resolution image and high-resolution image from thetop-resolution image, and then generates the user-requested composedimage, with a portion of the high-resolution image corresponding to thearea of interest overlaid on the base-resolution image at a locationcorresponding to the area of interest. When the server compositionmethod is used, the request processing module 1240 requests a composedimage from the image management module 1220. The request processingmodule 1240 sends the composed image generated using any of thesemethods to the user interface module for display on display 1260.

For the collaborative method, request processing module 1240 on a seconduser's client device 110 can be configured to request selectionparameters for an image from the network interface module 1210 set by afirst user for the second user, and to receive the selection parametersfrom the network interface module 1210. The request processing module1240 can also be configured to generate the selection parameters usingalgorithms. The request processing module 1240 can be configured to usethe selection parameters to generate a composed image specified by theselection parameters, and send the composed image to the user interfacemodule 1230 for display on display 1260. In generating the composedimage, the request processing module can be configured to use either thesuccessive download method, client downscaling method, or servercomposition method described above.

Those of skill in the art will appreciate that the various illustrativemodules and method steps described in connection with the abovedescribed figures and the embodiments disclosed herein can often beimplemented as electronic hardware, software, firmware or combinationsof the foregoing. To clearly illustrate this interchangeability ofhardware and software, various illustrative modules and method stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled persons can implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the invention. In addition, the grouping offunctions within a module or step is for ease of description. Specificfunctions can be moved from one module or step to another withoutdeparting from the invention.

Moreover, the various illustrative modules and method steps described inconnection with the embodiments disclosed herein can be implemented orperformed with hardware such as a general purpose processor, a digitalsignal processor (“DSP”), an application specific integrated circuit(“ASIC”), field programmable gate array (“FPGA”) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor is hardware and can be amicroprocessor, but in the alternative, the processor can be anyhardware processor controller, microcontroller. A processor can also beimplemented as a combination of computing devices, for example, acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

Additionally, the steps of a method or algorithm described in connectionwith the embodiments disclosed herein can be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module can reside in computer orcontroller accessible on computer-readable storage media including RAMmemory, flash memory, ROM memory, EPROM memory, EEPROM memory,registers, hard disk, a removable disk, a CD-ROM, or any other form ofstorage medium including a network storage medium. An exemplary storagemedium can be coupled to the processor such the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium can be integral to the processor. Theprocessor and the storage medium can also reside in an ASIC. Accordingto some embodiments, a software module can reside in a non-transitorycomputer-readable storage media.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent exemplary embodiments of theinvention and are therefore representative of the subject matter whichis broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments and that the scope of the present invention isaccordingly limited by nothing other than the appended claims.

1. A computer-implemented method for displaying a portion of ahigh-resolution image in the context of a base-resolution image, whereinone or more processors of a client device are programmed to perform thesteps comprising: sending a request to a server over a network for animage; receiving the image from the server over the network; generatinga base-resolution image from the received image; displaying thebase-resolution image on a display; receiving a request to display anarea of interest of the base-resolution image in high resolution;sending a request to the server over the network for a high-resolutionimage that corresponds to at least the area of interest of thebase-resolution image; receiving the high-resolution image from theserver over the network; displaying at least a portion of thehigh-resolution image corresponding to the area of interest as anoverlay of the base-resolution image at a location that corresponds tothe area of interest, wherein the overlay comprises a virtual lens;tracking movements of a cursor controlled by a pointing device over thebase-resolution image; moving the virtual lens with respect to thebase-resolution image based on a location of the cursor relative to thebase-resolution image; and updating the at least a portion of thehigh-resolution image displayed by the virtual lens based on thelocation of the cursor relative to the base-resolution image, whereinthe base-resolution image and the high-resolution image each compriseone or more images.
 2. The method of claim 1, wherein a resolution ofthe base-resolution image is less than a resolution of amaximum-resolution image generated on, input to, or stored on theserver.
 3. The method of claim 2, wherein a resolution of thehigh-resolution image is less than or equal to a resolution of themaximum-resolution image, and wherein the resolution of thehigh-resolution image is greater than the resolution of thebase-resolution image.
 4. The method of claim 1, wherein a resolution ofthe base-resolution image or the high-resolution image is selected, atleast in part, based on capabilities of the client device or network. 5.The method of claim 1, further comprising: receiving a request to resizethe virtual lens; resizing the virtual lens; determining whether alarger portion of the high-resolution image is required; sending arequest to the server for a larger portion of the high-resolution imageif a larger portion of the high-resolution image is required; receivingthe larger portion of the high-resolution image from the server; anddisplaying the larger portion of the high-resolution image in thevirtual lens.
 6. The method of claim 1, further comprising: receiving arequest to change a shape of the virtual lens to a requested shape;rendering the virtual lens to have the requested shape; determiningwhether a larger portion of the high-resolution image is required;sending a request to the server for a larger portion of thehigh-resolution image if a larger portion of the high-resolution imageis required; receiving the larger portion of the high-resolution imagefrom the server; and displaying the larger portion of thehigh-resolution image in the virtual lens.
 7. The method of claim 1,further comprising: receiving a request to change a resolution of thehigh-resolution image displayed by the virtual lens; sending a requestto the server for an image at the requested resolution corresponding toat least the area of interest of the base-resolution image; receivingthe image at the requested resolution from the server; and displaying atleast a portion of the image at the requested resolution as an overlayof the base-resolution image at a location that corresponds to the areaof interest.
 8. The method of claim 1, further comprising freezing aposition of the virtual lens with respect to the base-resolution imagein response to a user command.
 9. The method of claim 8, furthercomprising unfreezing the position of the previously frozen virtual lenswith respect to the base-resolution image in response to a user command.10. The method of claim 1, further comprising rendering a border aroundthe virtual lens to demarcate the virtual lens from the base-resolutionimage.
 11. The method of claim 1, wherein displaying the at least aportion of the high-resolution image comprises rendering the virtuallens such that the virtual lens is centered over the area of interest.12. The method of claim 11, wherein rendering the virtual lens such thatthe virtual lens is centered over the area of interest comprises:determining whether at least a portion of the virtual lens would beoutside a border of the base-resolution image if the virtual lens wererendered centered over the area of interest; if at least a portion ofthe virtual lens would be outside a border of the base-resolution image,determining an offset location for the virtual lens where the virtuallens would not be outside of the border of the base-resolution image;and rendering the virtual lens such that the virtual lens and the atleast a portion of the high-resolution image displayed within it iscentered over the offset location.
 13. The method of claim 1, furthercomprising adjusting a size, shape, or position of the virtual lens toimprove the function of an application in which the virtual lens isbeing used.
 14. The method of claim 1, further comprising hiding thevirtual lens in response to a user command.
 15. The method of claim 1,further comprising showing the previously hidden virtual lens inresponse to a user command.
 16. The method of claim 1, furthercomprising rendering an opaque plane between the virtual lens and theunderlying base-resolution image, wherein the opaque plane can berendered as visible while waiting to receive the high-resolution imagefrom the server after the request for the high-resolution image has beensent to the server.
 17. The method of claim 1, wherein receiving thehigh-resolution image from the server comprises receiving only a portionof the high-resolution image that contains the area of interest.
 18. Themethod of claim 1, further comprising: identifying a resolution level orarea of interest that a user of the client device is likely to request;and sending a request to the server for a high-resolution image at theidentified resolution level or area of interest.
 19. The method of claim1, further comprising: identifying one or more additional images that auser of the client device is likely to request for generating thebase-resolution image; and sending a request to the server for theidentified one or more additional images in order to preload the imageson the client device before the user requests the one or more additionalimages.
 20. The method of claim 1, wherein at least one of the one ormore high-resolution images comprises a high-resolution video and atleast one of the one or more base-resolution images comprises abase-resolution video.
 21. The method of claim 20, wherein displayingthe at least a portion of the high-resolution image comprisessynchronizing a frame rate and a currently displayed frame of thehigh-resolution video with a frame-rate and currently displayed frame ofthe base-resolution video.
 22. The method of claim 1, wherein one ormore requested images are saved in a memory of the client device forlater use.
 23. A computer-implemented method for displaying a portion ofa high-resolution image in the context of a base-resolution image,wherein one or more processors of a client device are programmed toperform the steps comprising: sending a request to a server over anetwork for an image; receiving the image from the server over thenetwork; generating a base-resolution image from the received image;displaying the base-resolution image on a display; receiving a requestto display an area of interest of the base-resolution image in highresolution; sending a request to the server over the network for atop-resolution image that corresponds to at least the area of interestof the base-resolution image; receiving the top-resolution image fromthe server over the network; generating a high-resolution image from thetop-resolution image; displaying at least a portion of thehigh-resolution image corresponding to the area of interest as anoverlay on the base-resolution image at a location that corresponds tothe area of interest, wherein the overlay comprises a virtual lens;tracking movements of a cursor controlled by a pointing device over thebase-resolution image; moving the virtual lens with respect to thebase-resolution image based on a location of the cursor relative to thebase-resolution image; and updating the at least a portion of thehigh-resolution image displayed by the virtual lens based on thelocation of the cursor relative to the base-resolution image, whereinthe base-resolution image, the top-resolution image, and thehigh-resolution image each comprise one or more images.
 24. The methodof claim 23, wherein a resolution of the requested top-resolution imageis less than or equal to a maximum resolution generated on, input to, orstored on the server.
 25. The method of claim 23, wherein a resolutionof the base-resolution image is less than a resolution of thetop-resolution image.
 26. The method of claim 23, wherein a resolutionof the high-resolution image is less than or equal to a resolution ofthe top-resolution image, and wherein the resolution of thehigh-resolution image is greater than a resolution of thebase-resolution image.
 27. The method of claim 23, wherein a resolutionof the base-resolution image, the high-resolution image, or thetop-resolution image is selected, at least in part, based oncapabilities of the client device or network.
 28. The method of claim23, further comprising: receiving a request to resize the virtual lens;resizing the virtual lens; generating a portion of the high-resolutionimage at a size and in a shape that matches that of the virtual lens;and displaying the portion of the high-resolution image in the virtuallens.
 29. The method of claim 23, further comprising: receiving arequest to change a shape of the virtual lens to a requested shape; andrendering the virtual lens to have the requested shape; generating aportion of the high-resolution image at a size and in a shape thatmatches that of the virtual lens; and displaying the portion of thehigh-resolution image in the virtual lens.
 30. The method of claim 23,further comprising: receiving a request to change a resolution of thehigh-resolution image displayed by the virtual lens; generating ahigh-resolution image at the requested resolution based on thetop-resolution image; and displaying at least a portion of thehigh-resolution image corresponding to the area of interest at therequested resolution in the virtual lens.
 31. The method of claim 23,further comprising freezing a position of the virtual lens with respectto the base-resolution image in response to a user command.
 32. Themethod of claim 31, further comprising unfreezing the position of thevirtual lens with respect to the base-resolution image in response to auser command.
 33. The method of claim 23, further comprising hiding thevirtual lens in response to a user command.
 34. The method of claim 33,further comprising showing the previously hidden virtual lens inresponse to a user command.
 35. The method of claim 23, furthercomprising rendering a border around the virtual lens to demarcate thevirtual lens from the base-resolution image.
 36. The method of claim 23,wherein displaying the at least a portion of the high-resolution imagecomprises rendering the virtual lens such that the virtual lens iscentered over the area of interest.
 37. The method of claim 36, whereinrendering the virtual lens such that the virtual lens is centered overthe area of interest comprises: determining whether at least a portionof the virtual lens would be outside a border of the base-resolutionimage if the virtual lens were rendered centered over the area ofinterest; if at least a portion of the virtual lens would be outside aborder of the base-resolution image, determining an offset location forthe virtual lens where the virtual lens would not be outside of theborder of the base-resolution image; and rendering the virtual lens suchthat the virtual lens and the at least a portion of the high-resolutionimage displayed within it is centered over the offset location.
 38. Themethod of claim 23, further comprising adjusting a size, shape, orposition of the virtual lens to improve the function of an applicationin which the virtual lens is being used.
 39. The method of claim 23,further comprising: identifying one or more additional images that auser of the client device is likely to request for generating thebase-resolution image or the high-resolution image; and sending arequest to the server for the identified one or more additional imagesin order to preload the images on the client device before the userrequests the one or more additional images.
 40. The method of claim 23,wherein at least one of the one or more high-resolution images comprisesa high-resolution video and at least one of the one or morebase-resolution images comprises a base-resolution video.
 41. The methodof claim 40, wherein displaying the at least a portion of thehigh-resolution image comprises synchronizing a frame rate and acurrently displayed frame of the high-resolution video with a frame-rateand currently displayed frame of the base-resolution video.
 42. Themethod of claim 23, wherein one or more requested images are saved in amemory of the client device for later use.
 43. The method of claim 23,wherein displaying the base-resolution image comprises determiningwhether the base-resolution image exceeds the size of a display regionin which the base-resolution image is to be displayed, and displaying aportion of the base-resolution image within the display region; andwherein moving the virtual lens comprises determining whether thevirtual lens has reached an edge of the display region, and, if thevirtual lens has reached the edge of the display region, stoppingmovement of the virtual lens and scrolling the base-resolution image inan opposite direction as a movement indicated by the pointing device.44. The method of claim 43, wherein scrolling the base-resolution imagein the opposite direction as the movement indicated by the pointingdevice comprises scrolling the base-resolution image in the oppositedirection as the movement indicated by the pointing device until themovement indication by the pointing device stops or an edge of thebase-resolution image aligns with the edge of the display region. 45.The method of claim 23, wherein the requested image, the received image,the base-resolution image, the top-resolution image, and thehigh-resolution image each comprise a plurality of images.
 46. Themethod of claim 1, wherein displaying the base-resolution imagecomprises determining whether the base-resolution image exceeds the sizeof a display region in which the base-resolution image is to bedisplayed, and displaying a portion of the base-resolution image withinthe display region; and wherein moving the virtual lens comprisesdetermining whether the virtual lens has reached an edge of the displayregion, and, if the virtual lens has reached the edge of the displayregion, stopping movement of the virtual lens and scrolling thebase-resolution image in an opposite direction as a movement indicatedby the pointing device.
 47. The method of claim 46, wherein scrollingthe base-resolution image in the opposite direction as the movementindicated by the pointing device comprises scrolling the base-resolutionimage in the opposite direction as the movement indicated by thepointing device until the movement indication by the pointing devicestops or an edge of the base-resolution image aligns with the edge ofthe display region.
 48. The method of claim 1, wherein the requestedimage, the received image, the base-resolution image, and thehigh-resolution image each comprise a plurality of images.
 49. Acomputer-implemented method for displaying a portion of ahigh-resolution image in the context of a base-resolution image, whereinone or more processors are programmed to perform the steps comprising:sending a request to a server over a network for a base-resolutionimage; receiving the base-resolution image from the server over thenetwork; displaying the base-resolution image on a display of the clientdevice; receiving a request to display an area of interest of thebase-resolution image in high resolution; sending a request to theserver over the network for a high-resolution image that corresponds toat least the area of interest of the base-resolution image; receivingthe high-resolution image from the server over the network; displayingat least a portion of the high-resolution image corresponding to thearea of interest as an overlay of the base-resolution image at alocation that corresponds to the area of interest, wherein the overlaycomprises a virtual lens; tracking movements of a cursor controlled by apointing device over the base-resolution image at the client device;moving the virtual lens with respect to the base-resolution image basedon a location of the cursor relative to the base-resolution image; andupdating the at least a portion of the high-resolution image displayedby the virtual lens based on the location of the cursor relative to thebase-resolution image; wherein the base-resolution image and thehigh-resolution image each comprise one or more images.
 50. The methodof claim 49, wherein a resolution of the base-resolution image is lessthan a resolution of a maximum-resolution image generated on, input to,or stored on the server.
 51. The method of claim 50, wherein aresolution of the high-resolution image is less than or equal to aresolution of the maximum-resolution image, and wherein the resolutionof the high-resolution image is greater than the resolution of thebase-resolution image.
 52. The method of claim 49, wherein a resolutionof the base-resolution image or the high-resolution image is selected,at least in part, based on capabilities of the client device or network.53. The method of claim 49, further comprising: receiving a request toresize the virtual lens; resizing the virtual lens; determining whethera larger portion of the high-resolution image is required; sending arequest to the server for a larger portion of the high-resolution imageif a larger portion of the high-resolution image is required; receivingthe larger portion of the high-resolution image from the server; anddisplaying the larger portion of the high-resolution image in thevirtual lens.
 54. The method of claim 49, further comprising: receivinga request to change a shape of the virtual lens to a requested shape;rendering the virtual lens to have the requested shape; determiningwhether a larger portion of the high-resolution image is required;sending a request to the server for a larger portion of thehigh-resolution image if a larger portion of the high-resolution imageis required; receiving the larger portion of the high-resolution imagefrom the server; and displaying the larger portion of thehigh-resolution image in the virtual lens.
 55. The method of claim 49,further comprising: receiving a request to change a resolution of thehigh-resolution image displayed by the virtual lens; sending a requestto the server for an image at the requested resolution corresponding toat least the area of interest of the base-resolution image; receivingthe image at the requested resolution from the server; and displaying atleast a portion of the image at the requested resolution as an overlayof the base-resolution image at a location that corresponds to the areaof interest.
 56. The method of claim 49, further comprising freezing aposition of the virtual lens with respect to the base-resolution imagein response to a user command.
 57. The method of claim 56, furthercomprising unfreezing the position of the previously frozen virtual lenswith respect to the base-resolution image in response to a user command.58. The method of claim 49, further comprising rendering a border aroundthe virtual lens to demarcate the virtual lens from the base-resolutionimage.
 59. The method of claim 49, wherein displaying the at least aportion of the high-resolution image comprises rendering the virtuallens such that the virtual lens is centered over the area of interest.60. The method of claim 59, wherein rendering the virtual lens such thatthe virtual lens is centered over the area of interest comprises:determining whether at least a portion of the virtual lens would beoutside a border of the base-resolution image if the virtual lens wererendered centered over the area of interest; if at least a portion ofthe virtual lens would be outside a border of the base-resolution image,determining an offset location for the virtual lens where the virtuallens would not be outside of the border of the base-resolution image;and rendering the virtual lens such that the virtual lens and the atleast a portion of the high-resolution image displayed within it iscentered over the offset location.
 61. The method of claim 49, furthercomprising adjusting a size, shape, or position of the virtual lens toimprove the function of an application in which the virtual lens isbeing used.
 62. The method of claim 49, further comprising hiding thevirtual lens in response to a user command.
 63. The method of claim 49,further comprising showing the previously hidden virtual lens inresponse to a user command.
 64. The method of claim 49, furthercomprising rendering an opaque plane between the virtual lens and theunderlying base-resolution image, wherein the opaque plane can berendered as visible while waiting to receive the high-resolution imagefrom the server after the request for the high-resolution image has beensent to the server.
 65. The method of claim 49, wherein receiving thehigh-resolution image from the server comprises receiving only a portionof the high-resolution image that contains the area of interest.
 66. Themethod of claim 49, further comprising: identifying a resolution levelor area of interest that a user of the client device is likely torequest; and sending a request to the server for a high-resolution imageat the identified resolution level or area of interest.
 67. The methodof claim 49, further comprising: identifying one or more additionalimages that a user of the client device is likely to request forgenerating the base-resolution image; and sending a request to theserver for the identified one or more additional images in order topreload the images on the client device before the user requests the oneor more additional images.
 68. The method of claim 49, wherein at leastone of the one or more high-resolution images comprises ahigh-resolution video and at least one of the one or morebase-resolution images comprises a base-resolution video.
 69. The methodof claim 68, wherein displaying the at least a portion of thehigh-resolution image comprises synchronizing a frame rate and acurrently displayed frame of the high-resolution video with a frame-rateand currently displayed frame of the base-resolution video.
 70. Themethod of claim 49, wherein one or more requested images are saved in amemory of the client device for later use.
 71. The method of claim 49,wherein displaying the base-resolution image comprises determiningwhether the base-resolution image exceeds the size of a display regionin which the base-resolution image is to be displayed, and displaying aportion of the base-resolution image within the display region; andwherein moving the virtual lens comprises determining whether thevirtual lens has reached an edge of the display region, and, if thevirtual lens has reached the edge of the display region, stoppingmovement of the virtual lens and scrolling the base-resolution image inan opposite direction as a movement indicated by the pointing device.72. The method of claim 71, wherein scrolling the base-resolution imagein the opposite direction as the movement indicated by the pointingdevice comprises scrolling the base-resolution image in the oppositedirection as the movement indicated by the pointing device until themovement indication by the pointing device stops or an edge of thebase-resolution image aligns with the edge of the display region. 73.The method of claim 49, wherein the requested image, the received image,the base-resolution image, and the high-resolution image each comprise aplurality of images.
 74. A computer-implemented method for displaying aportion of a high-resolution image in the context of a base-resolutionimage, wherein one or more processors are programmed to perform thesteps comprising: sending a request to a server over a network for atop-resolution image; receiving the top-resolution image from the serverover the network; generating a base-resolution image based on thetop-resolution image received from the server; displaying thebase-resolution image on a display of the client device; receiving arequest to display an area of interest of the base-resolution image inhigh resolution; generating a high-resolution image based on thetop-resolution image received from the server; displaying at least aportion of the high-resolution image corresponding to the area ofinterest as an overlay on the base-resolution image at a location thatcorresponds to the area of interest, wherein the overlay comprises avirtual lens; tracking movements of a cursor controlled by a pointingdevice over the base-resolution image at the client device; moving thevirtual lens with respect to the base-resolution image based on alocation of the cursor relative to the base-resolution image; andupdating the at least a portion of the high-resolution image displayedby the virtual lens based on the location of the cursor relative to thebase-resolution image; wherein the top-resolution image, thebase-resolution image, and the high-resolution image each comprise oneor more images.
 75. The method of claim 74, wherein a resolution of thebase-resolution image is less than a resolution of a maximum-resolutionimage generated on, input to, or stored on the server.
 76. The method ofclaim 75, wherein a resolution of the high-resolution image is less thanor equal to a resolution of the maximum-resolution image, and whereinthe resolution of the high-resolution image is greater than theresolution of the base-resolution image.
 77. The method of claim 74,wherein a resolution of the base-resolution image or the high-resolutionimage is selected, at least in part, based on capabilities of the clientdevice or network.
 78. The method of claim 74, further comprising:receiving a request to resize the virtual lens; resizing the virtuallens; determining whether a larger portion of the high-resolution imageis required; sending a request to the server for a larger portion of thehigh-resolution image if a larger portion of the high-resolution imageis required; receiving the larger portion of the high-resolution imagefrom the server; and displaying the larger portion of thehigh-resolution image in the virtual lens.
 79. The method of claim 74,further comprising: receiving a request to change a shape of the virtuallens to a requested shape; rendering the virtual lens to have therequested shape; determining whether a larger portion of thehigh-resolution image is required; sending a request to the server for alarger portion of the high-resolution image if a larger portion of thehigh-resolution image is required; receiving the larger portion of thehigh-resolution image from the server; and displaying the larger portionof the high-resolution image in the virtual lens.
 80. The method ofclaim 74, further comprising: receiving a request to change a resolutionof the high-resolution image displayed by the virtual lens; sending arequest to the server for an image at the requested resolutioncorresponding to at least the area of interest of the base-resolutionimage; receiving the image at the requested resolution from the server;and displaying at least a portion of the image at the requestedresolution as an overlay of the base-resolution image at a location thatcorresponds to the area of interest.
 81. The method of claim 74, furthercomprising freezing a position of the virtual lens with respect to thebase-resolution image in response to a user command.
 82. The method ofclaim 81, further comprising unfreezing the position of the previouslyfrozen virtual lens with respect to the base-resolution image inresponse to a user command.
 83. The method of claim 74, furthercomprising rendering a border around the virtual lens to demarcate thevirtual lens from the base-resolution image.
 84. The method of claim 74,wherein displaying the at least a portion of the high-resolution imagecomprises rendering the virtual lens such that the virtual lens iscentered over the area of interest.
 85. The method of claim 84, whereinrendering the virtual lens such that the virtual lens is centered overthe area of interest comprises: determining whether at least a portionof the virtual lens would be outside a border of the base-resolutionimage if the virtual lens were rendered centered over the area ofinterest; if at least a portion of the virtual lens would be outside aborder of the base-resolution image, determining an offset location forthe virtual lens where the virtual lens would not be outside of theborder of the base-resolution image; and rendering the virtual lens suchthat the virtual lens and the at least a portion of the high-resolutionimage displayed within it is centered over the offset location.
 86. Themethod of claim 74, further comprising adjusting a size, shape, orposition of the virtual lens to improve the function of an applicationin which the virtual lens is being used.
 87. The method of claim 74,further comprising hiding the virtual lens in response to a usercommand.
 88. The method of claim 74, further comprising showing thepreviously hidden virtual lens in response to a user command.
 89. Themethod of claim 74, further comprising rendering an opaque plane betweenthe virtual lens and the underlying base-resolution image, wherein theopaque plane can be rendered as visible while waiting to receive thehigh-resolution image from the server after the request for thehigh-resolution image has been sent to the server.
 90. The method ofclaim 74, wherein receiving the high-resolution image from the servercomprises receiving only a portion of the high-resolution image thatcontains the area of interest.
 91. The method of claim 74, furthercomprising: identifying a resolution level or area of interest that auser of the client device is likely to request; and sending a request tothe server for a high-resolution image at the identified resolutionlevel or area of interest.
 92. The method of claim 74, furthercomprising: identifying one or more additional images that a user of theclient device is likely to request for generating the base-resolutionimage; and sending a request to the server for the identified one ormore additional images in order to preload the images on the clientdevice before the user requests the one or more additional images. 93.The method of claim 74, wherein at least one of the one or morehigh-resolution images comprises a high-resolution video and at leastone of the one or more base-resolution images comprises abase-resolution video.
 94. The method of claim 93, wherein displayingthe at least a portion of the high-resolution image comprisessynchronizing a frame rate and a currently displayed frame of thehigh-resolution video with a frame-rate and currently displayed frame ofthe base-resolution video.
 95. The method of claim 74, wherein one ormore requested images are saved in a memory of the client device forlater use.
 96. The method of claim 74, wherein displaying thebase-resolution image comprises determining whether the base-resolutionimage exceeds the size of a display region in which the base-resolutionimage is to be displayed, and displaying a portion of thebase-resolution image within the display region; and wherein moving thevirtual lens comprises determining whether the virtual lens has reachedan edge of the display region, and, if the virtual lens has reached theedge of the display region, stopping movement of the virtual lens andscrolling the base-resolution image in an opposite direction as amovement indicated by the pointing device.
 97. The method of claim 96,wherein scrolling the base-resolution image in the opposite direction asthe movement indicated by the pointing device comprises scrolling thebase-resolution image in the opposite direction as the movementindicated by the pointing device until the movement indication by thepointing device stops or an edge of the base-resolution image alignswith the edge of the display region.
 98. The method of claim 74, whereinthe requested image, the received image, the base-resolution image, andthe high-resolution image each comprise a plurality of images.